10-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2020 or

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

001-03140

(Commission File Number)

Northern States Power Company

(Exact name of registrant as specified in its charter)

Wisconsin			39-0508315
(State or other jurisdiction or incorporation or organization)			(I.R.S. Employer Identification No.)
1414 West Hamilton Avenue	Eau Claire	Wisconsin	54701
(Address of principal executive offices)			(Zip Code)

715	839-2625
(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol	Name of each exchange on which registered
N/A	N/A	N/A

Securities registered pursuant to section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. ☒ Yes ☐ No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. ☐ Yes ☒ No

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. ☒ Yes ☐ No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). ☒ Yes ☐ No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act. ☐ Large accelerated filer ☐ Accelerated filer ☒ Non-accelerated filer ☐ Smaller reporting company ☐ Emerging growth company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C.7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). ☐ Yes ☒ No

As of Feb. 17, 2021, 933,000 shares of common stock, par value $100 per share, were outstanding, all of which were held by Xcel Energy Inc., a Minnesota corporation.

DOCUMENTS INCORPORATED BY REFERENCE

The information required by Item 14 of Form 10-K is set forth under the heading “Independent Registered Public Accounting Firm – Audit and Non-Audit Fees” in Xcel Energy Inc.’s definitive Proxy Statement for the 2021 Annual Meeting of Stockholders which definitive Proxy Statement is expected to be filed with the SEC on or about April 6, 2021. Such information set forth under such heading is incorporated herein by this reference hereto.

Northern States Power Company meets the conditions set forth in General Instructions I(1)(a) and (b) of Form 10-K and is therefore filing this form with the reduced disclosure format permitted by General Instruction I(2).

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TABLE OF CONTENTS

PART I
Item 1 —	Business	3
	Definition of Abbreviations	3
	Forward-Looking Statements	3
	Where to Find More Information	4
	Overview	4
	Electric Operations	4
	Natural Gas Operations	7
	General	7
	Public Utility Regulation	8
	Environmental	8
	Employees	8
Item 1A —	Risk Factors	8
Item 1B —	Unresolved Staff Comments	14
Item 2 —	Properties	15
Item 3 —	Legal Proceedings	15
Item 4 —	Mine Safety Disclosures	15
PART II
Item 5 —	Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities	15
Item 6 —	Selected Financial Data	15
Item 7 —	Management’s Discussion and Analysis of Financial Condition and Results of Operations	15
Item 7A —	Quantitative and Qualitative Disclosures About Market Risk	18
Item 8 —	Financial Statements and Supplementary Data	18
Item 9 —	Changes in and Disagreements with Accountants on Accounting and Financial Disclosure	40
Item 9A —	Controls and Procedures	41
Item 9B —	Other Information	41
PART III
Item 10 —	Directors, Executive Officers and Corporate Governance	41
Item 11 —	Executive Compensation	41
Item 12 —	Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters	41
Item 13 —	Certain Relationships and Related Transactions, and Director Independence	41
Item 14 —	Principal Accountant Fees and Services	41
PART IV
Item 15 —	Exhibit and Financial Statement Schedules	42
Item 16 —	Form 10-K Summary	43
Signatures		44

This Form 10-K is filed by NSP-Wisconsin. NSP-Wisconsin is a wholly owned subsidiary of Xcel Energy Inc. Additional information on Xcel Energy is available in various filings with the SEC. This report should be read in its entirety.

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PART I

ITEM 1 — BUSINESS

Definitions of Abbreviations

Xcel Energy Inc.’s Subsidiaries and Affiliates (current and former)
e prime	e prime inc.
NSP-Minnesota	Northern States Power Company, a Minnesota corporation
NSP System	The electric production and transmission system of NSP-Minnesota and NSP-Wisconsin operated on an integrated basis and managed by NSP-Minnesota
NSP-Wisconsin	Northern States Power Company, a Wisconsin corporation
PSCo	Public Service Company of Colorado
SPS	Southwestern Public Service Company
Utility subsidiaries	NSP-Minnesota, NSP-Wisconsin, PSCo and SPS
Xcel Energy	Xcel Energy Inc. and its subsidiaries

Federal and State Regulatory Agencies
D.C. Circuit	United States Court of Appeals for the District of Columbia Circuit
DOT	Department of Transportation
EPA	United States Environmental Protection Agency
FERC	Federal Energy Regulatory Commission
IRS	Internal Revenue Service
MPSC	Michigan Public Service Commission
NERC	North American Electric Reliability Corporation
NRC	Nuclear Regulatory Commission
PHMSA	Pipeline and Hazardous Materials Safety Administration
PSCW	Public Service Commission of Wisconsin
SEC	Securities and Exchange Commission

Other
ADIT	Accumulated deferred income taxes
AFUDC	Allowance for funds used during construction
ARO	Asset retirement obligation
ASC	FASB Accounting Standards Codification
ASU	FASB Accounting Standards Update
C&I	Commercial and Industrial
CapX2020	Alliance of electric cooperatives, municipals and investor-owned utilities in the upper Midwest involved in a joint transmission line planning and construction effort
CEO	Chief executive officer
CFO	Chief financial officer
COVID-19	Novel coronavirus
CWA	Clean Water Act
CWIP	Construction work in progress

DSM	Demand side management
EMANI	European Mutual Association for Nuclear Insurance
ETR	Effective tax rate
FASB	Financial Accounting Standards Board
GAAP	Generally accepted accounting principles
GHG	Greenhouse gas
INPO	Institute of Nuclear Power Operations
ITC	Investment tax credit
MDL	Multi-district litigation
MGP	Manufactured gas plant
MISO	Midcontinent Independent System Operator, Inc.
Native load	Customer demand of retail and wholesale customers whereby a utility has an obligation to serve under statute or long-term contract
NAV	Net asset value
NEIL	Nuclear Electric Insurance Ltd.
NOL	Net operating loss
O&M	Operating and maintenance
PGA	Purchased gas adjustment
PI	Prairie Island nuclear generating plant
PPA	Purchased power agreement
REC	Renewable energy credit
ROE	Return on equity
RTO	Regional Transmission Organization
SERP	Supplemental executive retirement plan
TCJA	2017 federal tax reform enacted as Public Law No: 115-97, commonly referred to as the Tax Cuts and Jobs Act
TO	Transmission owner
VIE	Variable interest entity
WOTUS	Waters of the U.S.

Measurements
Bcf	Billion cubic feet
KV	Kilovolts
KWh	Kilowatt hours
MMBtu	Million British thermal units
MW	Megawatts
MWh	Megawatt hours

Forward-Looking Statements

Except for the historical statements contained in this report, the matters discussed herein are forward-looking statements that are subject to certain risks, uncertainties and assumptions. Such forward-looking statements, including future sales, future bad debt expense, future operating performance, estimated base capital expenditures and financing plans, projected capital additions and forecasted annual revenue requirements with respect to rider filings and expectations regarding regulatory proceedings, as well as assumptions and other statements are intended to be identified in this document by the words “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “objective,” “outlook,” “plan,” “project,” “possible,” “potential,” “should,” “will,” “would” and similar expressions. Actual results may vary materially. Forward-looking statements speak only as of the date they are made, and we expressly disclaim any obligation to update any forward-looking information.

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The following factors, in addition to those discussed elsewhere in this Annual Report on Form 10-K for the fiscal year ended Dec. 31, 2020 (including risk factors listed from time to time by NSP-Wisconsin in reports filed with the SEC, including “Risk Factors” in Item 1A of this Annual Report on Form 10-K hereto), could cause actual results to differ materially from management expectations as suggested by such forward-looking information: uncertainty around the impacts and duration of the COVID-19 pandemic; operational safety, including nuclear generation; successful long-term operational planning; commodity risks associated with energy markets and production; rising energy prices and fuel costs; qualified employee work force and third-party contractor factors; ability to recover costs; changes in regulation; reductions in our credit ratings and the cost of maintaining certain contractual relationships; general economic conditions, including inflation rates, monetary fluctuations and their impact on capital expenditures and the ability of NSP-Wisconsin and its subsidiaries to obtain financing on favorable terms; availability or cost of capital; our customers’ and counterparties’ ability to pay their debts to us; assumptions and costs relating to funding our employee benefit plans and health care benefits; tax laws; effects of geopolitical events, including war and acts of terrorism; cyber security threats and data security breaches; seasonal weather patterns; changes in environmental laws and regulations; climate change and other weather; natural disaster and resource depletion, including compliance with any accompanying legislative and regulatory changes; and costs of potential regulatory penalties.

Where to Find More Information

NSP-Wisconsin is a wholly owned subsidiary of Xcel Energy Inc. and Xcel Energy’s website address is www.xcelenergy.com. Xcel Energy makes available, free of charge through its website, its annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and all amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934 as soon as reasonably practicable after the reports are electronically filed with or furnished to the SEC. The SEC maintains an internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically at http://www.sec.gov. The information on Xcel Energy’s website is not a part of, or incorporated by reference in, this annual report on Form 10-K.

Overview

Electric customers	0.3 million		NSP-Wisconsin was incorporated in 1901 under the laws of Wisconsin. NSP-Wisconsin conducts business in Wisconsin and Michigan and generates, transmits, distributes and sells electricity. NSP-Minnesota and NSP-Wisconsin electric operations are managed on the NSP System. NSP-Wisconsin also purchases, transports, distributes and sells natural gas to retail customers and transports customer-owned natural gas.
Natural gas customers	0.1 million
Total assets	$2.9 billion
Rate Base (estimated)	$1.8 billion
ROE (net income / average stockholder's equity)	10.52%
Electric generating capacity	548 MW
Gas storage capacity	3.8 Bcf
Electric transmission lines (conductor miles)	12,288 miles
Electric distribution lines (conductor miles)	27,611 miles
Natural gas transmission lines	3 miles
Natural gas distribution lines	2,492 miles

Electric Operations

Electric operations consist of energy supply, generation, transmission and distribution activities. NSP-Wisconsin had electric sales volume of 6,609 (millions of KWh), 0.3 million customers and electric revenues of $855 (millions of dollars) for 2020.

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Sales/Revenue Statistics (a)

	2020			2019
KWh sales per retail customer	24,999			25,910
Revenue per retail customer	$	2,580		$	2,653
Residential revenue per KWh	13.30		¢	13.34		¢
Large C&I revenue per KWh	7.53		¢	7.45		¢
Small C&I revenue per KWh	9.99		¢	9.99		¢
Total retail revenue per KWh	10.32		¢	10.24		¢

(a) See Note 6 to the consolidated financial statements for further information.

Owned and Purchased Energy Generation — 2020

Electric Energy Sources

Total electric generation by source (including energy market purchases) for the year ended Dec. 31, 2020:

*Distributed generation from the Solar*Rewards® program is not included (approximately 43 million KWh for 2020).

Carbon–Free Energy — NSP System

The NSP System’s carbon–free energy portfolio includes nuclear, wind, hydroelectric, biomass and solar power from both owned generating facilities and PPAs. Carbon–free percentages will vary year over year based on system additions, weather, system demand and transmission constraints.

See Item 2 — Properties for further information.

Carbon–free energy as a percentage of total energy for 2020:

* Includes biomass and hydroelectric

Wind

Owned — Owned and operated wind farms with corresponding capacity:

2020		2019
Wind Farms	Capacity (a)	Wind Farms	Capacity (b)
11	1,540 MW	7	1,079 MW

(a)    Summer 2020 net dependable capacity.

(b)    Summer 2019 net dependable capacity.

PPAs — Number of PPAs with capacity range:

2020		2019
PPAs	Range	PPAs	Range
129	1 MW — 206 MW	131	1 MW — 206 MW

Capacity — Wind capacity:

2020	2019
3,348 MW	2,767 MW

Average Cost (Owned) — Average cost per MWh of wind energy from owned generation:

2020	2019
$23	$35

Average Cost (PPAs) — Average cost per MWh of wind energy under existing PPAs:

2020	2019
$38	$41

Wind Development

NSP-System’s placed approximately 460 MW of owned wind and a 200 MW PPA into service during 2020:

Project	Capacity
Blazing Star 1	200 MW (a)(b)
Crowned Ridge 2	192 MW (a)(b)
Community Wind North	26 MW (a)(b)
Jeffers	43 MW (a)(b)
PPA	200 MW (c)

(a)Summer 2020 net dependable capacity.

(b)Values disclosed are the maximum generation levels for these wind units. Capacity is attainable only when wind conditions are sufficiently available (on-demand net dependable capacity is zero).

(c)Based on contracted capacity.

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NSP-System’s currently has approximately 1,450 MW of owned wind under development or construction. In addition, the NSP-System expects to add approximately 450 MW of planned PPAs.

Project	Capacity	Estimated Completion
Dakota Range	300 MW	2021
Freeborn	200 MW	2021
Blazing Star 2	200 MW	2021
Nobles	200 MW	2022
Pleasant Valley	200 MW	2024
Border Winds	150 MW	2024
Grand Meadow	100 MW	2023
Mower	99 MW	2021
Various PPAs	~450 MW	2021

Solar

Solar energy PPAs:

Type	Capacity
Distributed Generation	899 MW
Utility-Scale	268 MW
Total	1,167 MW

Average Cost (PPAs) — Average cost per MWh of solar energy under existing PPAs:

2020	2019
$90	$81

Nuclear

NSP System has two nuclear plants (owned by NSP-Minnesota) with approximately 1,700 MW of total 2020 net summer dependable capacity. NSP-Minnesota secures contracts for uranium concentrates, uranium conversion, uranium enrichment and fuel fabrication to operate its nuclear plants. NSP-Minnesota uses varying contract lengths as well as multiple producers for uranium concentrates, conversion services and enrichment services to minimize potential impacts caused by supply interruptions due to geographical and world political issues.

Nuclear Fuel Cost

Delivered cost per MMBtu of nuclear fuel consumed for owned electric generation and the percentage of total fuel requirements:

	Nuclear
	Cost		Percent
2020	$	0.80	51	%
2019	0.81		45

Other Carbon-Free Energy — NSP System

The NSP System’s other carbon-free energy portfolio includes hydro from owned generating facilities.

See Item 2 — Properties for further information.

Fossil Fuel Energy — NSP System

The NSP System’s fossil fuel energy portfolio includes coal and natural gas power from both owned generating facilities and PPAs.

Coal

NSP System has three coal plants with approximately 2,400 MW of total 2020 net summer dependable capacity.

Approved and proposed coal plant retirements:

Approved
Year	Plant Unit	Capacity
2023	Sherco 2	682 MW
2026	Sherco 1	680 MW

Proposed
Year	Plant Unit	Capacity
2028	A.S King	511 MW
2030	Sherco 3	517 MW (a)

(a)    Based on NSP System’s ownership percentage.

Coal Fuel Cost

Delivered cost per MMBtu of coal consumed for owned electric generation and the percentage of total fuel requirements:

	Coal (a)
	Cost		Percent
2020	$	1.97	31	%
2019	2.02		36

(a)    Includes refuse-derived fuel and wood for the NSP System.

Natural Gas

The NSP System has eight natural gas plants with approximately 2,800 MW of total 2020 net summer dependable capacity.

Natural gas supplies, transportation and storage services for power plants are procured to provide an adequate supply of fuel. Remaining requirements are procured through a liquid spot market. Generally, natural gas supply contracts have variable pricing that is tied to natural gas indices. Natural gas supply and transportation agreements include obligations for the purchase and/or delivery of specified volumes or payments in lieu of delivery.

Natural Gas Cost

Delivered cost per MMBtu of natural gas consumed for owned electric generation and the percentage of total fuel requirements:

	Natural Gas
	Cost		Percent
2020	$	2.67	17	%
2019	3.09		19

Capacity and Demand

Uninterrupted system peak demand and occurrence date:

System Peak Demand (in MW)
2020		2019
8,571	July 8	8,774	July 19

Transmission

Transmission lines deliver electricity over long distances from power sources to transmission substations closer to homes and businesses. A strong transmission system ensures continued reliable and affordable service, ability to meet state and regional energy policy goals, and support for a diverse generation mix, including renewable energy. NSP-Wisconsin owns more than 12,300 conductor miles of transmission lines.

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During 2020, NSP-Wisconsin completed the following transmission project:

Project	Miles	Size
Prentice to Structure	8	115 KV
Lufkin to Naples	13	69 KV
Belgrade to Ironwood	13	35 KV
Cornucopia to Bayfield Phase 2	5	35 KV

Notable upcoming transmission project:

Project	Miles	Size	Completion Date
Turtle Lake Almena	4	69 KV	2021
Bayfield Second Circuit	19	35 KV	2022

Distribution

Distribution lines allow electricity to travel at lower voltages from substations directly to homes and businesses. NSP-Wisconsin has a vast distribution network, owning and operating approximately 28,000 conductor miles of distribution lines across our service territory, both above ground and underground. To continue providing reliable, affordable electric service and enable more flexibility for customers, we are working to digitize the distribution grid, while at the same time keeping it secure.

See Item 2 - Properties for further information.

Natural Gas Operations

Natural gas operations consist of purchase, transportation, and distribution of natural gas to end-use residential, C&I and transport customers. NSP-Wisconsin had natural gas deliveries of 21,096 (thousands of MMBtu), 0.1 million customers and natural gas revenues of $119 (millions of dollars) for 2020.

Sales/Revenue Statistics (a)

	2020		2019
MMBtu sales per retail customer	139.88		151.74
Revenue per retail customer	$	976.4	$	1,118.22
Residential revenue per MMBtu	8.91		9.31
C&I revenue per MMBtu	5.46		5.83
Transportation and other revenue per MMBtu	0.69		1.31

(a) See Note 6 to the consolidated financial statements for further information.

Capability and Demand

Natural gas supply requirements are categorized as firm or interruptible (customers with an alternate energy supply).

Maximum daily output (firm and interruptible) and occurrence date:

2020		2019
MMBtu	Date	MMBtu	Date
150,320	Dec. 24	166,009	Jan. 30

Natural Gas Supply and Costs

NSP-Wisconsin seeks natural gas supply, transportation and storage alternatives to yield a diversified portfolio, which increase flexibility, decrease interruption and financial risks and economical rates. In addition, NSP-Wisconsin conducts natural gas price hedging activities approved by its states’ commissions.

Average delivered cost per MMBtu of natural gas for regulated retail distribution:

2020		2019
$	3.08	$	3.49

NSP-Wisconsin has natural gas supply transportation and storage agreements that include obligations for purchase and/or delivery of specified volumes or to make payments in lieu of delivery.

General

Seasonality

Demand for electric power and natural gas is affected by seasonal differences in the weather. In general, peak sales of electricity occur in the summer months and peak sales of natural gas occur in the winter months. As a result, the overall operating results may fluctuate substantially on a seasonal basis. Additionally, NSP-Wisconsin’s operations have historically generated less revenues and income when weather conditions are milder in the winter and cooler in the summer.

Competition

NSP-Wisconsin is subject to public policies that promote competition and development of energy markets. NSP-Wisconsin’s industrial and large commercial customers have the ability to generate their own electricity. In addition, customers may have the option of substituting other fuels or relocating their facilities to a lower cost region.

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Customers have the opportunity to supply their own power with distributed generation including solar generation and in most jurisdictions can currently avoid paying for most of the fixed production, transmission and distribution costs incurred to serve them.

Wisconsin has incentives for the development of rooftop solar, community solar gardens and other distributed energy resources. Distributed generating resources are potential competitors to NSP-Wisconsin’s electric service business with these incentives and federal tax subsidies.

The FERC has continued to promote competitive wholesale markets through open access transmission and other means. NSP-Wisconsin’s wholesale customers can purchase their output from generation resources of competing suppliers or non-contracted quantities and use the transmission system of NSP-Wisconsin on a comparable basis to serve their native load.

FERC Order No. 1000 established competition for construction and operation of certain new electric transmission facilities. State utilities commissions have also created resource planning programs that promote competition for electricity generation resources used to provide service to retail customers.

NSP-Wisconsin has franchise agreements with cities subject to periodic renewal; however, a city could seek alternative means to access electric power or gas, such as municipalization. No municipalization activities are occurring presently.

While facing these challenges, NSP-Wisconsin believes its rates and services are competitive with alternatives currently available.

Public Utility Regulation

See Item 7 for discussion of public utility regulation.

Environmental

Environmental Regulation

Our facilities are regulated by federal and state agencies that have jurisdiction over air emissions, water quality, wastewater discharges, solid wastes and hazardous substances. Certain NSP-Wisconsin activities require registrations, permits, licenses, inspections and approvals from these agencies. NSP-Wisconsin has received necessary authorizations for the construction and continued operation of its generation, transmission and distribution systems. Our facilities operate in compliance with applicable environmental standards and related monitoring and reporting requirements. However, it is not possible to determine when or to what extent additional facilities or modifications of existing or planned facilities will be required as a result of changes to regulations, interpretations or enforcement policies or what effect future laws or regulations may have. We may be required to incur expenditures in the future for remediation of MGP and other sites if it is determined that prior compliance efforts are not sufficient.

NSP-Wisconsin must comply with emission levels that may require the purchase of emission allowances.

There are significant environmental regulations to encourage use of clean energy technologies and regulate emissions of GHGs. NSP-Wisconsin has undertaken numerous initiatives to meet current requirements and prepare for potential future regulations, reduce GHG emissions and respond to state renewable and energy efficiency goals. Future environmental regulations may result in substantial costs.

In July 2019, the EPA adopted the Affordable Clean Energy rule, which required states to develop plans by 2022 for GHG reductions from coal-fired power plants. In a Jan. 19, 2021 decision, the U.S. Court of Appeals for the D.C. Circuit issued a decision vacating and remanding the Affordable Clean Energy rule. That decision, if not successfully appealed or reconsidered, would allow the EPA to proceed with alternate regulation of coal-fired power plants, either reviving the Clean Power Plan or proposing additional regulation. It is too early to predict an outcome, but new rules could require substantial additional investment, even in plants slated for retirement. NSP-Wisconsin believes, based on prior state commission practices, the cost of these initiatives or replacement generation would be recoverable through rates.

NSP-Wisconsin seeks to address climate change and potential climate change regulation through efforts to reduce its GHG emissions in a balanced, cost-effective manner.

Employees

As of Dec. 31, 2020, NSP-Wisconsin had 540 full-time employees and no part-time employees, of which 394 were covered under collective-bargaining agreements.

ITEM 1A — RISK FACTORS

Xcel Energy, which includes NSP-Wisconsin, is subject to a variety of risks, many of which are beyond our control. Risks that may adversely affect the business, financial condition, results of operations or cash flows are described below. These risks should be carefully considered together with the other information set forth in this report and future reports that Xcel Energy files with the SEC.

Oversight of Risk and Related Processes

NSP-Wisconsin’s Board of Directors is responsible for the oversight of material risk and maintaining an effective risk monitoring process. Management and the Board of Directors have responsibility for overseeing the identification and mitigation of key risks.

At a threshold level, NSP-Wisconsin maintains a robust compliance program and promotes a culture of compliance beginning with the tone at the top. The risk mitigation process includes adherence to our code of conduct and compliance policies, operation of formal risk management structures and overall business management. NSP-Wisconsin further mitigates inherent risks through formal risk committees and corporate functions such as internal audit, and internal controls over financial reporting and legal.

Management identifies and analyzes risks to determine materiality and other attributes such as timing, probability and controllability. Identification and risk analysis occurs formally through risk assessment conducted by senior management, the financial disclosure process, hazard risk procedures, internal audit and compliance with financial and operational controls. Management also identifies and analyzes risk through the business planning process, development of goals and establishment of key performance indicators, including identification of barriers to implementing our strategy. The business planning process also identifies likelihood and mitigating factors to prevent the assumption of inappropriate risk to meet goals.

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Management communicates regularly with the Board of Directors and its sole stockholder regarding risk. Senior management presents and communicates a periodic risk assessment to the Board of Directors. The presentation and the discussion of the key risks provides information on the risks management believes are material, including financial impact, timing, likelihood and mitigating factors. The Board of Directors regularly reviews management’s key risk assessments, which includes areas of existing and future macroeconomic, financial, operational, policy, environmental and security risks.

Overall, oversight, management and mitigation of risk is an integral and continuous part of the Board of Directors’ governance of NSP-Wisconsin. Processes are in place to ensure appropriate risk oversight, as well as identification and consideration of new risks.

Risks Associated with Our Business

Operational Risks

Our natural gas and electric transmission and distribution operations involve numerous risks that may result in accidents and other operating risks and costs.

Our natural gas transmission and distribution activities include inherent hazards and operating risks, such as leaks, explosions, outages and mechanical problems. Our electric generation, transmission and distribution activities include inherent hazards and operating risks such as contact, fire and outages.

These risks could result in loss of life, significant property damage, environmental pollution, impairment of our operations and substantial financial losses. We maintain insurance against most, but not all, of these risks and losses. The occurrence of these events, if not fully covered by insurance, could have a material effect on our financial condition, results of operations and cash flows.

Other uncertainties and risks inherent in operating and maintaining NSP-Wisconsin's facilities include, but are not limited to:

•Risks associated with facility start-up operations, such as whether the facility will achieve projected operating performance on schedule and otherwise as planned.

•Failures in the availability, acquisition or transportation of fuel or other necessary supplies.

•The impact of unusual or adverse weather conditions and natural disasters, including, but not limited to, tornadoes, icing events, floods and droughts.

•Performance below expected or contracted levels of output or efficiency (e.g., performance guarantees).

•Availability of replacement equipment.

•Availability of adequate water resources and ability to satisfy water intake and discharge requirements.

•Inability to identify, manage properly or mitigate equipment defects.

•Use of new or unproven technology.

•Risks associated with dependence on a specific type of fuel or fuel source, such as commodity price risk, availability of adequate fuel supply and transportation and lack of available alternative fuel sources.

•Increased competition due to, among other factors, new facilities, excess supply, shifting demand and regulatory changes.

Additionally, compliance with existing and potential new regulations related to the operation and maintenance of our natural gas infrastructure could result in significant costs. The PHMSA is responsible for administering the DOT’s national regulatory program to assure the safe transportation of natural gas, petroleum and other hazardous materials by pipelines. The PHMSA continues to develop regulations and other approaches to risk management to assure safety in design, construction, testing, operation, maintenance and emergency response of natural gas pipeline infrastructure. We have programs in place to comply with the PHMSA regulations and systematically monitor and renew infrastructure over time, however, a significant incident or material finding of non-compliance could result in penalties and higher costs of operations.

Our natural gas and electric transmission and distribution operations are dependent upon complex information technology systems and network infrastructure, the failure of which could disrupt our normal business operations, which could have a material adverse effect on our ability to process transactions and provide services.

Our utility operations are subject to long-term planning and project risks.

Most electric utility investments are planned to be used for decades. Transmission and generation investments typically have long lead times and are planned well in advance of in-service dates and typically subject to long-term resource plans. These plans are based on numerous assumptions such as: sales growth, customer usage, commodity prices, economic activity, costs, regulatory mechanisms, customer behavior, available technology and public policy. Our long-term resource plan is dependent on our ability to obtain required approvals, develop necessary technical expertise, allocate and coordinate sufficient resources and adhere to budgets and timelines.

In addition, the long-term nature of both our planning and our asset lives are subject to risk. The electric utility sector is undergoing significant change (e.g, increases in energy efficiency, wider adoption of distributed generation and shifts away from fossil fuel generation to renewable generation). Customer adoption of these technologies and increased energy efficiency could result in excess transmission and generation resources, downward pressure on sales growth, and potentially stranded costs if we are not able to fully recover costs and investments.

Changing customer expectations and technologies are requiring significant investments in advanced grid infrastructure, which increases exposure to technology obsolescence. Additionally, evolving stakeholder preference for lower emissions from generation sources and end-uses, like heating, may put pressure on our ability to recover capital investments in natural gas generation and delivery.

The magnitude and timing of resource additions and changes in customer demand may not coincide with evolving customer preference for generation resources and end-uses, which introduces further uncertainty into long-term planning. Efforts to electrify the transportation and building sectors to reduce GHG emissions may result in higher electric demand and lower natural gas demand over time. Additionally, multiple states may not agree as to the appropriate resource mix, which may lead to costs to comply with one jurisdiction that are not recoverable across all jurisdictions served by the same assets.

We are subject to longer-term availability of inputs such as coal, natural gas, uranium and water to cool our facilities. Lack of availability of these resources could jeopardize long-term operations of our facilities or make them uneconomic to operate.

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We are subject to commodity risks and other risks associated with energy markets and energy production.

In the event fuel costs increase, customer demand could decline and bad debt expense may rise, which may have a material impact on our results of operations. Despite existing fuel recovery mechanisms, higher fuel costs could significantly impact our results of operations if costs are not recovered. Delays in the timing of the collection of fuel cost recoveries could impact our cash flows and liquidity.

A significant disruption in supply could cause us to seek alternative supply services at potentially higher costs and supply shortages may not be fully resolved, which could cause disruptions in our ability to provide services to our customers. Failure to provide service due to disruptions may also result in fines, penalties or cost disallowances through the regulatory process. Also, significantly higher energy or fuel costs relative to sales commitments could negatively impact our cash flows and results of operations.

We also engage in wholesale sales and purchases of electric capacity, energy and energy-related products as well as natural gas. In many markets, emission allowances and/or RECs are also needed to comply with various statutes and commission rulings. As a result, we are subject to market supply and commodity price risk.

Commodity price changes can affect the value of our commodity trading derivatives. We mark certain derivatives to estimated fair market value on a daily basis. Settlements can vary significantly from estimated fair values recorded and significant changes from the assumptions underlying our fair value estimates could cause earnings variability. The management of risks associated with hedging and trading is based, in part, on programs and procedures which utilize historical prices and trends.

Due to the inherent uncertainty involved in price movements and potential deviation from historical pricing, NSP-Wisconsin is unable to fully assure that its risk management programs and procedures would be effective to protect against all significant adverse market deviations. In addition, NSP-Wisconsin cannot fully assure that its controls will be effective against all potential risks, including, without limitation, employee misconduct. If such controls are not effective, NSP-Wisconsin’s results of operations, financial condition or cash flows could be materially impacted.

Failure to attract and retain a qualified workforce could have an adverse effect on operations.

Specialized knowledge is required of our technical employees for construction and operation of transmission, generation and distribution assets. Our business strategy is dependent on our ability to recruit, retain and motivate employees. There is competition and a tightening market for skilled employees. Failure to hire and adequately train replacement employees, including the transfer of significant internal historical knowledge and expertise to new employees or future availability and cost of contract labor may adversely affect the ability to manage and operate our business. Inability to attract and retain these employees could adversely impact our results of operations, financial condition or cash flows.

Our operations use third-party contractors in addition to employees to perform periodic and ongoing work.

We rely on third-party contractors to perform operations, maintenance and construction work. Our contractual arrangements with these contractors typically include performance standards, progress payments, insurance requirements and security for performance. Poor vendor performance could impact ongoing operations, restoration operations, our reputation and could introduce financial risk or risks of fines.

Although we do not own any nuclear generating facilities, because our production and transmission system is operated on an integrated basis with NSP-Minnesota’s (an affiliate of NSP-Wisconsin) production and transmission system, we may be subject to risks associated with NSP-Minnesota’s nuclear generation.

NSP-Minnesota has two nuclear generation plants, PI and Monticello. Risks of nuclear generation include:

•Hazards associated with the use of radioactive material in energy production, including management, handling, storage and disposal.

•Limitations on insurance available to cover losses that may arise in connection with nuclear operations, as well as obligations to contribute to an insurance pool in the event of damages at a covered U.S. reactor.

•Technological and financial uncertainties related to the costs of decommissioning nuclear plants may cause our funding obligations to change.

The NRC has authority to impose licensing and safety-related requirements for the operation of nuclear generation facilities, including the ability to impose fines and/or shut down a unit until compliance is achieved. NRC safety requirements could necessitate substantial capital expenditures or an increase in operating expenses. In addition, the INPO reviews NSP-Minnesota’s nuclear operations. Compliance with the INPO’s recommendations could result in substantial capital expenditures or a substantial increase in operating expenses.

If a nuclear incident did occur, it could have a material impact on our results of operations, financial condition or cash flows. Furthermore, non-compliance or the occurrence of a serious incident at other nuclear facilities could result in increased industry regulation, which may increase NSP-Minnesota’s compliance costs.

We share in the electric production and transmission costs of the NSP-Minnesota system, which is integrated with our system. Accordingly, our costs may be increased due to increased costs associated with NSP-Minnesota’s system.

Our electric production and transmission system is managed on an integrated basis with the electric production and transmission system of NSP-Minnesota. Pursuant to the Interchange Agreement between NSP-Minnesota and us, we share, on a proportional basis, all costs related to the generation and transmission facilities of the entire integrated NSP System, including capital costs. Accordingly, if the costs to operate the NSP System increase, or revenue decreases, whether as a result of state or federally mandated improvements or otherwise, our costs could also increase and our revenues could decrease and we cannot guarantee a full recovery of such costs through our rates at the time the costs are incurred.

We are a wholly owned subsidiary of Xcel Energy Inc. Xcel Energy Inc. can exercise substantial control over our dividend policy and business and operations and may exercise that control in a manner that may be perceived to be adverse to our interests.

All of the members of our Board of Directors, as well as many of our executive officers, are officers of Xcel Energy Inc. Our Board makes determinations with respect to a number of significant corporate events, including the payment of our dividends.

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We have historically paid quarterly dividends to Xcel Energy Inc. In 2020, 2019 and 2018 we paid $70 million, $84 million and $91 million of dividends to Xcel Energy Inc., respectively. If Xcel Energy Inc.’s cash requirements increase, our Board of Directors could decide to increase the dividends we pay to Xcel Energy Inc. to help support Xcel Energy Inc.’s cash needs. This could adversely affect our liquidity. The most restrictive dividend limitation for NSP-Wisconsin is imposed by our state regulatory commission. NSP-Wisconsin cannot pay annual dividends in excess of certain amounts if its calendar year average equity-to-total capitalization ratio is or falls below the state commission authorized level.

See Note 5 to the consolidated financial statements for further information.

Financial Risks

Our profitability depends on our ability to recover costs from our customers and changes in regulation may impair our ability to recover costs from our customers.

We are subject to comprehensive regulation by federal and state utility regulatory agencies, including siting and construction of facilities, customer service and the rates that we can charge customers.

The profitability of our operations is dependent on our ability to recover the costs of providing energy and utility services and earn a return on our capital investment. Our rates are generally regulated and based on an analysis of our costs incurred in a test year. We are subject to both future and historical test years depending upon the regulatory jurisdiction. Thus, the rates we are allowed to charge may or may not match our costs at any given time. Rate regulation is premised on providing an opportunity to earn a reasonable rate of return on invested capital.

There can also be no assurance that our regulatory commissions will judge all our costs to be prudent, which could result in disallowances, or that the regulatory process will always result in rates that will produce full recovery. Overall, management believes prudently incurred costs are recoverable given the existing regulatory framework. However, there may be changes in the regulatory environment that could impair our ability to recover costs historically collected from customers, or we could exceed caps on capital costs required by commissions and result in less than full recovery.

Changes in the long-term cost-effectiveness or to the operating conditions of our assets may result in early retirements of utility facilities. While regulation typically provides cost recovery relief for these types of changes, there is no assurance that regulators would allow full recovery of all remaining costs.

In a continued low interest rate environment there has been increased downward pressure on allowed ROE. Conversely, higher than expected inflation or tariffs may increase costs of construction and operations. Also, rising fuel costs could increase the risk that we will not be able to fully recover our fuel costs from our customers.

Adverse regulatory rulings or the imposition of additional regulations could have an adverse impact on our results of operations and materially affect our ability to meet our financial obligations, including debt payments.

Any reductions in our credit ratings could increase our financing costs and the cost of maintaining certain contractual relationships.

We cannot be assured that our current credit ratings will remain in effect, or that a rating will not be lowered or withdrawn by a rating agency. Significant events including disallowance of costs, lower returns on equity, changes to equity ratios and impacts of tax policy may impact our cash flows and credit metrics, potentially resulting in a change in our credit ratings.

In addition, our credit ratings may change as a result of the differing methodologies or change in the methodologies used by the various rating agencies. Any credit ratings downgrade could lead to higher borrowing costs and could impact our ability to access capital markets. Also, we may enter into contracts that require posting of collateral or settlement if credit ratings fall below investment grade.

We are subject to capital market and interest rate risks.

Utility operations require significant capital investment. As a result, we frequently need to access capital markets. Any disruption in capital markets could have a material impact on our ability to fund our operations. Capital market disruption and financial market distress could prevent us from issuing short-term commercial paper, issuing new securities or cause us to issue securities with unfavorable terms and conditions, such as higher interest rates. Higher interest rates on short-term borrowings with variable interest rates could also have an adverse effect on our operating results.

We are subject to credit risks.

Credit risk includes the risk that our customers will not pay their bills, which may lead to a reduction in liquidity and an increase in bad debt expense. Credit risk is comprised of numerous factors including the price of products and services provided, the economy and unemployment rates.

Credit risk also includes the risk that counterparties that owe us money or product will become insolvent and may breach their obligations. Should the counterparties fail to perform, we may be forced to enter into alternative arrangements. In that event, our financial results could be adversely affected and incur losses.

We may have direct credit exposure as part of our local gas distribution company supply activity to financial institutions trading for their own accounts or issuing collateral support on behalf of other counterparties. We may also have some indirect credit exposure due to participation in organized markets, (e.g., Southwest Power Pool, Inc, PJM Interconnection, LLC, MISO and Electric Reliability Council of Texas), in which any credit losses are socialized to all market participants.

We have additional indirect credit exposure to financial institutions from letters of credit provided as security by power suppliers under various purchased power contracts. If any of the credit ratings of the letter of credit issuers were to drop below investment grade, the supplier would need to replace that security with an acceptable substitute. If the security were not replaced, the party could be in default under the contract.

As we are a subsidiary of Xcel Energy Inc., we may be negatively affected by events impacting the credit or liquidity of Xcel Energy Inc. and its affiliates.

If either Standard & Poor’s Global Ratings or Moody’s Investor Services were to downgrade Xcel Energy Inc.’s debt securities below investment grade, it would increase Xcel Energy Inc.’s cost of capital and restrict its access to the capital markets. This could limit Xcel Energy Inc.’s ability to contribute equity or make loans to us, or may cause Xcel Energy Inc. to seek additional or accelerated funding from us in the form of dividends. If such event were to occur, we may need to seek alternative sources of funds to meet our cash needs.

As of Dec. 31, 2020, Xcel Energy Inc. and its utility subsidiaries had approximately $19.6 billion of long-term debt and $1.0 billion of short-term debt and current maturities. Xcel Energy Inc. provides various guarantees and bond indemnities supporting some of its subsidiaries by guaranteeing the payment or performance by these subsidiaries for specified agreements or transactions.

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Xcel Energy also has other contingent liabilities resulting from various tax disputes and other matters. Xcel Energy Inc.’s exposure under the guarantees is based upon the net liability of the relevant subsidiary under the specified agreements or transactions. The majority of Xcel Energy Inc.’s guarantees limit its exposure to a maximum amount that is stated in the guarantees. 

As of Dec. 31, 2020, Xcel Energy had guarantees outstanding with a $2 million maximum stated amount and immaterial exposure. Xcel Energy also had additional guarantees of $60 million at Dec. 31, 2020 for performance and payment of surety bonds for the benefit of itself and its subsidiaries, with total exposure that cannot be estimated at this time. If Xcel Energy Inc. were to become obligated to make payments under these guarantees and bond indemnities or become obligated to fund other contingent liabilities, it could limit Xcel Energy Inc.’s ability to contribute equity or make loans to us or may cause Xcel Energy Inc. to seek additional or accelerated funding from us in the form of dividends. If such event were to occur, we may need to seek alternative sources of funds to meet our cash needs.

Increasing costs of our defined benefit retirement plans and employee benefits may adversely affect our results of operations, financial condition or cash flows.

We have defined benefit pension and postretirement plans that cover most of our employees. Assumptions related to future costs, return on investments, interest rates and other actuarial assumptions have a significant impact on our funding requirements of these plans. Estimates and assumptions may change. In addition, the Pension Protection Act sets the minimum funding requirements for defined benefit pension plans. Therefore, our funding requirements and contributions may change in the future. Also, the payout of a significant percentage of pension plan liabilities in a single year due to high numbers of retirements or employees leaving NSP-Wisconsin would trigger settlement accounting and could require NSP-Wisconsin to recognize incremental pension expense related to unrecognized plan losses in the year liabilities are paid. Changes in industry standards utilized in key assumptions (e.g., mortality tables) could have a significant impact on future obligations and benefit costs.

Increasing costs associated with health care plans may adversely affect our results of operations.

Increasing levels of large individual health care claims and overall health care claims could have an adverse impact on our results of operations, financial condition and/or cash flows. Health care legislation could also significantly impact our benefit programs and costs.

Federal tax law may significantly impact our business.

NSP-Wisconsin collects estimated federal, state and local tax payments through their regulated rates. Changes to federal tax law may benefit or adversely affect our earnings and customer costs. Tax depreciable lives and the value of various tax credits or the timeliness of their utilization may impact the economics or selection of resources. If tax rates are increased, there could be timing delays before regulated rates provide for recovery of such tax increases in revenues. In addition, certain IRS tax policies such as tax normalization may impact our ability to economically deliver certain types of resources relative to market prices.

Macroeconomic Risks

Economic conditions impact our business.

Our operations are affected by local, national and worldwide economic conditions, which correlates to customers/sales growth (decline). Economic conditions may be impacted by insufficient financial sector liquidity leading to potential increased unemployment, which may impact customers’ ability to pay their bills which could lead to additional bad debt expense.

Additionally, NSP-Wisconsin faces competitive factors, which could have an adverse impact on our financial condition, results of operations and cash flows. Further, worldwide economic activity impacts the demand for basic commodities necessary for utility infrastructure, which may inhibit our ability to acquire sufficient supplies. We operate in a capital intensive industry and federal trade policy could significantly impact the cost of materials we use. There may be delays before these additional material costs can be recovered in rates.

We face risks related to health epidemics and other outbreaks, which may have a material effect on our financial condition, results of operations and cash flows.

The global outbreak of COVID-19 is impacting countries, communities, supply chains and markets. A high degree of uncertainty continues to exist regarding the pandemic, the duration and magnitude of business restrictions, re-shut downs, if any, and the level and pace of economic recovery. While we are implementing contingency plans, there are no guarantees these plans will be sufficient to offset the impact of COVID-19.

Although the impact of the pandemic to the 2020 results was largely mitigated due to management’s actions, we cannot ultimately predict whether it will have a material impact on our future liquidity, financial condition or results of operations. Nor can we predict the impact of the virus on the health of our employees, our supply chain or our ability to recover higher costs associated with managing through the pandemic. The impact of COVID-19 may exacerbate other risks discussed herein, which could have a material effect on us. The situation is evolving and additional impacts may arise.

Operations could be impacted by war, terrorism or other events.

Our generation plants, fuel storage facilities, transmission and distribution facilities and information and control systems may be targets of terrorist activities. Any disruption could impact operations or result in a decrease in revenues and additional costs to repair and insure our assets. These disruptions could have a material impact on our financial condition, results of operations or cash flows. The potential for terrorism has subjected our operations to increased risks and could have a material effect on our business. We have already incurred increased costs for security and capital expenditures in response to these risks. The insurance industry has also been affected by these events and the availability of insurance may decrease. In addition, insurance may have higher deductibles, higher premiums and more restrictive policy terms.

A disruption of the regional electric transmission grid, interstate natural gas pipeline infrastructure or other fuel sources, could negatively impact our business, brand and reputation. Because our facilities are part of an interconnected system, we face the risk of possible loss of business due to a disruption caused by the actions of a neighboring utility.

We also face the risks of possible loss of business due to significant events such as severe storms, severe temperature extremes, wildfires, widespread pandemic, generator or transmission facility outage, pipeline rupture, railroad disruption, operator error, sudden and significant increase or decrease in wind generation or a workforce disruption.

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In addition, major catastrophic events throughout the world may disrupt our business. Xcel Energy participates in a global supply chain, which includes materials and components that are globally sourced. A prolonged disruption could result in the delay of equipment and materials that may impact our ability to reliably serve our customers.

A major disruption could result in a significant decrease in revenues and additional costs to repair assets, which could have a material impact on our results of operations, financial condition or cash flows.

NSP-Wisconsin participates in grid security and emergency response exercises (GridEx). These efforts, led by the NERC, test and further develop the coordination, threat sharing and interaction between utilities and various government agencies relative to potential cyber and physical threats against the nation’s electric grid.

A cyber incident or security breach could have a material effect on our business.

We operate in an industry that requires the continued operation of sophisticated information technology, control systems and network infrastructure. In addition, we use our systems and infrastructure to create, collect, use, disclose, store, dispose of and otherwise process sensitive information, including company data, customer energy usage data, and personal information regarding customers, employees and their dependents, contractors and other individuals.

Our generation, transmission, distribution and fuel storage facilities, information technology systems and other infrastructure or physical assets, as well as information processed in our systems (e.g., information regarding our customers, employees, operations, infrastructure and assets) could be affected by cyber security incidents, including those caused by human error. Our industry has been the target of several attacks on operational systems and has seen an increased volume and sophistication of cyber security incidents from international activist organizations, Nation States and individuals. Cyber security incidents could harm our businesses by limiting our generating, transmitting and distributing capabilities, delaying our development and construction of new facilities or capital improvement projects to existing facilities, disrupting our customer operations or causing the release of customer information, all of which would likely receive state and federal regulatory scrutiny and could expose us to liability.

Our generation, transmission systems and natural gas pipelines are part of an interconnected system. Therefore, a disruption caused by the impact of a cyber security incident of the regional electric transmission grid, natural gas pipeline infrastructure or other fuel sources of our third-party service providers’ operations, could also negatively impact our business.

Our supply chain for procurement of digital equipment and services may expose software or hardware to these risks and could result in a breach or significant costs of remediation. We are unable to quantify the potential impact of cyber security threats or subsequent related actions. Cyber security incidents and regulatory action could result in a material decrease in revenues and may cause significant additional costs (e.g., penalties, third-party claims, repairs, insurance or compliance) and potentially disrupt our supply and markets for natural gas, oil and other fuels.

We maintain security measures to protect our information technology and control systems, network infrastructure and other assets. However, these assets and the information they process may be vulnerable to cyber security incidents, including asset failure or unauthorized access to assets or information. A failure or breach of our technology systems or those of our third-party service providers could disrupt critical business functions and may negatively impact our business, our brand, and our reputation. The cyber security threat is dynamic and evolves continually, and our efforts to prioritize network protection may not be effective given the constant changes to threat vulnerability.

Our operating results may fluctuate on a seasonal and quarterly basis and can be adversely affected by milder weather.

Our electric and natural gas utility businesses are seasonal and weather patterns can have a material impact on our operating performance. Demand for electricity is often greater in the summer and winter months associated with cooling and heating. Because natural gas is heavily used for residential and commercial heating, the demand depends heavily upon weather patterns. A significant amount of natural gas revenues are recognized in the first and fourth quarters related to the heating season. Accordingly, our operations have historically generated less revenues and income when weather conditions are milder in the winter and cooler in the summer. Unusually mild winters and summers could have an adverse effect on our financial condition, results of operations, or cash flows.

Public Policy Risks

We may be subject to legislative and regulatory responses to climate change, with which compliance could be difficult and costly.

Legislative and regulatory responses related to climate change may create financial risk as our facilities may be subject to additional regulation at either the state or federal level in the future. International agreements could additionally lead to future federal or state regulations.

In 2015, the United Nations Framework Convention on Climate Change reached consensus among 190 nations on an agreement (the Paris Agreement) that establishes a framework for GHG mitigation actions by all countries, with a goal of holding the increase in global average temperature to below 2º Celsius above pre-industrial levels and an aspiration to limit the increase to 1.5º Celsius. The Biden Administration will establish a new nationally determined contribution for the United States. The Paris Agreement could result in future additional GHG reductions in the United States. In addition, the Biden Administration has announced plans to implement new climate change programs, including potential regulation of GHG emissions targeting the utility industry.

The Biden Administration has also announced a one year suspension of new oil and natural gas drilling on federal lands to allow for a review of oil and gas leasing regulations. The form of these regulations is uncertain, but, depending on the requirements imposed in the short and long term, they could impose substantial costs on our oil and gas customers or result in substantial increases to the cost of fuel we use in our electricity and gas businesses.

Many states and localities continue to pursue their own climate policies. The steps Xcel Energy has taken to date to reduce GHG emissions, including energy efficiency measures, adding renewable generation or retiring or converting coal plants to natural gas, occurred under state-endorsed resource plans, renewable energy standards and other state policies.

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We may be subject to climate change lawsuits. An adverse outcome could require substantial capital expenditures and possibly require payment of substantial penalties or damages. Defense costs associated with such litigation can also be significant and could affect results of operations, financial condition or cash flows if such costs are not recovered through regulated rates.

If our regulators do not allow us to recover all or a part of the cost of capital investment or the O&M costs incurred to comply with the mandates, it could have a material effect on our results of operations, financial condition or cash flows.

Increased risks of regulatory penalties could negatively impact our business.

The Energy Act increased civil penalty authority for violation of FERC statutes, rules and orders. The FERC can impose penalties of up to $1.3 million per violation per day, particularly as it relates to energy trading activities for both electricity and natural gas. In addition, NERC electric reliability standards and critical infrastructure protection requirements are mandatory and subject to potential financial penalties. Also, the PHMSA, Occupational Safety and Health Administration and other federal agencies have the authority to assess penalties.

In the event of serious incidents, these agencies may pursue penalties. In addition, certain states have the authority to impose substantial penalties. If a serious reliability, cyber or safety incident did occur, it could have a material effect on our results of operations, financial condition or cash flows.

Environmental Risks

We are subject to environmental laws and regulations, with which compliance could be difficult and costly.

We are subject to environmental laws and regulations that affect many aspects of our operations, including air emissions, water quality, wastewater discharges and the generation, transport and disposal of solid wastes and hazardous substances. Laws and regulations require us to obtain permits, licenses, and approvals and to comply with a variety of environmental requirements.

Environmental laws and regulations can also require us to restrict or limit the output of facilities or the use of certain fuels, shift generation to lower-emitting facilities, install pollution control equipment, clean up spills and other contamination and correct environmental hazards. Failure to meet requirements of environmental mandates may result in fines or penalties. We may be required to pay all or a portion of the cost to remediate sites where our past activities, or the activities of other parties, caused environmental contamination.

Changes in environmental policies and regulations or regulatory decisions may result in early retirements of our generation facilities. While regulation typically provides relief for these types of changes, there is no assurance that regulators would allow full recovery of all remaining costs.

We are subject to mandates to provide customers with clean energy, renewable energy and energy conservation offerings. It could have a material effect on our results of operations, financial condition or cash flows if our regulators do not allow us to recover the cost of capital investment or O&M costs incurred to comply with the requirements.

In addition, existing environmental laws or regulations may be revised and new laws or regulations may be adopted. We may also incur additional unanticipated obligations or liabilities under existing environmental laws and regulations.

We are subject to physical and financial risks associated with climate change and other weather, natural disaster and resource depletion impacts.

Climate change can create physical and financial risk. Physical risks include changes in weather conditions and extreme weather events.

Our customers’ energy needs vary with weather. To the extent weather conditions are affected by climate change, customers’ energy use could increase or decrease. Increased energy use due to weather changes may require us to invest in generating assets, transmission and infrastructure. Decreased energy use due to weather changes may result in decreased revenues.

Climate change may impact the economy, which could impact our sales and revenues. The price of energy has an impact on the economic health of our communities. The cost of additional regulatory requirements, such as regulation of GHG, could impact the availability of goods and prices charged by our suppliers, which would normally be borne by consumers through higher prices for energy and purchased goods. To the extent financial markets view climate change and emissions of GHGs as a financial risk, this could negatively affect our ability to access capital markets or cause us to receive less than ideal terms and conditions.

Severe weather impacts our service territories, primarily when thunderstorms, flooding, tornadoes, wildfires and snow or ice storms occur. Extreme weather conditions in general require system backup and can contribute to increased system stress, including service interruptions. Extreme weather conditions creating high energy demand may raise electricity prices, increasing the cost of energy we provide to our customers.

To the extent the frequency of extreme weather events increases, this could increase our cost of providing service. Periods of extreme temperatures could impact our ability to meet demand. Changes in precipitation resulting in droughts or water shortages could adversely affect our operations. Drought conditions also contribute to the increase in wildfire risk from our electric generation facilities.

While we carry liability insurance, given an extreme event, if NSP-Wisconsin was found to be liable for wildfire damages, amounts that potentially exceed our coverage could negatively impact our results of operations, financial condition or cash flows. Drought or water depletion could adversely impact our ability to provide electricity to customers, cause early retirement of power plants and increase the cost for energy. We may not recover all costs related to mitigating these physical and financial risks.

ITEM 1B — UNRESOLVED STAFF COMMENTS

None.

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ITEM 2 — PROPERTIES

Virtually all of the utility plant property of NSP-Wisconsin is subject to the lien of its first mortgage bond indenture.

Station, Location and Unit	Fuel	Installed	MW (a)
Steam:
Bay Front-Ashland, WI, 2 Units	Wood/Natural Gas	1948 - 1956	41
French Island-La Crosse, WI, 2 Units	Wood/Refuse	1940 - 1948	16	(b)
Combustion Turbine:
French Island-La Crosse, WI, 2 Units	Oil	1974	122
Wheaton-Eau Claire, WI, 5 Units	Natural Gas/Oil	1973	234
Hydro:
Various locations, 63 Units	Hydro	Various	135
		Total	548

(a)Summer 2020 net dependable capacity.

(b)Refuse-derived fuel is made from municipal solid waste.

Electric utility overhead and underground transmission and distribution lines (measured in conductor miles) at Dec. 31, 2020:

Conductor Miles
Transmission
345 KV	3,337
161 KV	1,823
115 KV	1,822
Less than 115 KV	5,306
Total Transmission	12,288
Distribution
Less than 115 KV	27,611
Total	39,899

NSP-Wisconsin had 204 electric utility transmission and distribution substations at Dec. 31, 2020.

Natural gas utility mains at Dec. 31, 2020:

Miles
Transmission	3
Distribution	2,492

ITEM 3 — LEGAL PROCEEDINGS

NSP-Wisconsin is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Wisconsin’s financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.

See Note 10 to the consolidated financial statements, Item 1 and Item 7 for further information.

ITEM 4 — MINE SAFETY DISCLOSURES

None.

PART II

ITEM 5 — MARKET FOR REGISTRANT’S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES.

NSP-Wisconsin is a wholly owned subsidiary of Xcel Energy Inc. and there is no market for its common equity securities.

The dividends declared during 2020 and 2019 were as follows:

(Millions of Dollars)	2020		2019
First quarter	$	17	$	23
Second quarter	20		16
Third quarter	18		27
Fourth quarter	19		15

ITEM 6 — SELECTED FINANCIAL DATA

Omitted per conditions set forth in general instructions I(1)(a) and (b) of Form 10-K for wholly owned subsidiaries (reduced disclosure format).

ITEM 7 — MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Discussion of financial condition and liquidity for NSP-Wisconsin is omitted per conditions set forth in general instructions I(1)(a) and (b) of Form 10-K for wholly owned subsidiaries. It is replaced with management’s narrative analysis and the results of operations for the current year as set forth in general instructions I(2)(a) of Form 10-K for wholly owned subsidiaries (reduced disclosure format).

Non-GAAP Financial Measures

The following discussion includes financial information prepared in accordance with GAAP, as well as certain non-GAAP financial measures such as, electric margin, natural gas margin, and ongoing earnings.  Generally, a non-GAAP financial measure is a measure of a company’s financial performance, financial position or cash flows that excludes (or includes) amounts that are adjusted from measures calculated and presented in accordance with GAAP. NSP-Wisconsin’s management uses non-GAAP measures for financial planning and analysis, for reporting of results to the Board of Directors, in determining performance-based compensation and communicating its earnings outlook to analysts and investors. Non-GAAP financial measures are intended to supplement investors’ understanding of our performance and should not be considered alternatives for financial measures presented in accordance with GAAP. These measures are discussed in more detail below and may not be comparable to other companies’ similarly titled non-GAAP financial measures.

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Electric and Natural Gas Margins

Electric margin is presented as electric revenues less electric fuel and purchased power expenses. Natural gas margin is presented as natural gas revenues less the cost of natural gas sold and transported. Expenses incurred for electric fuel and purchased power and the cost of natural gas are generally recovered through various regulatory recovery mechanisms. As a result, changes in these expenses are generally offset in operating revenues.

Management believes electric and natural gas margins provide the most meaningful basis for evaluating our operations because they exclude the revenue impact of fluctuations in these expenses. These margins can be reconciled to operating income, a GAAP measure, by including other operating revenues, cost of sales-other, O&M expenses, conservation and DSM expenses, depreciation and amortization and taxes (other than income taxes).

Earnings Adjusted for Certain Items (Ongoing Earnings)

Ongoing earnings reflect adjustments to GAAP earnings (net income) for certain items

We use these non-GAAP financial measures to evaluate and provide details of NSP-Minnesota’s core earnings and underlying performance. We believe these measurements are useful to investors to evaluate the actual and projected financial performance and contribution of NSP-Wisconsin. For the years ended Dec. 31, 2020 and 2019, there were no adjustments to GAAP earnings and therefore GAAP earnings equal ongoing earnings.

Results of Operations

2020 Comparison with 2019

NSP-Wisconsin’s net income was $107 million for 2020 compared with $79 million for 2019. The increase was driven by higher electric margin (2020 Wisconsin Fuel Settlement offset lower sales due to COVID-19) and lower O&M expenses, partially offset by increased depreciation and lower natural gas margin.

Electric Margin

Electric revenues and fuel and purchased power expenses are impacted by fluctuations in the price of natural gas, coal and uranium. However, these fluctuations have minimal impact on margin due to fuel recovery mechanisms.

Electric Revenues and Margin:

(Millions of Dollars)	2020		2019
Electric revenues	$	855	$	845
Electric fuel and purchased power	(392)		(405)
Electric margin	$	463	$	440

Changes in Electric Margin:

(Millions of Dollars)	2020 vs. 2019
Regulatory rate outcomes	$	29
2019 tax reform credits (offset in income tax)	7
Interchange agreement billings with NSP-Minnesota	3
Estimated impact of weather	1
Sales and demand	(10)
Purchased capacity costs	(2)
Other (net)	(5)
Total increase in electric margin	$	23

Natural Gas Margin

Natural gas expense varies with changing sales and cost of natural gas. However, fluctuations in the cost of natural gas has minimal impact on margin due to cost recovery mechanisms.

Natural Gas Revenues and Margin:

(Millions of Dollars)	2020		2019
Natural gas revenues	$	119	$	136
Cost of natural gas sold and transported	(53)		(65)
Natural gas margin	$	66	$	71

Natural Gas Margin:

(Millions of Dollars)	2020 vs. 2019
Estimated impact of weather	$	(5)
Regulatory rate outcomes	(3)
Retail sales growth	2
Other (net)	1
Total decrease in natural gas margin	$	(5)

Non-Fuel Operating Expenses and Other Items

O&M Expenses — O&M expenses decreased $10 million, or 5%, for 2020 compared with 2019. The decrease was primarily due to cost mitigation efforts to offset the negative impacts of COVID-19 including allocation of workforce, material and supply management, performance of maintenance, as well as, lower interchange billings with NSP-Minnesota and employee healthcare expenses.

Depreciation and Amortization — Depreciation and amortization increased $18 million, or 13%, for 2020 compared with 2019. The increase is mainly due to increased MGP amortization and normal system expansion (mainly electric distribution and transmission). This was partially offset by deferred tax liability amortization.

AFUDC, Equity and Debt — AFUDC increased $3 million for 2020 compared with 2019. The increase was due to various electric transmission and distribution plant construction projects.

Income Taxes — Income tax expense decreased $23 million for 2020. The decrease was primarily driven by an increase in plant-related regulatory differences and nonplant ADIT amortization. The ETR was (7.0%) for 2020 compared with 16.8% for 2019, largely due to the adjustments referenced above.

16

Public Utility Regulation

The FERC and state and local regulatory commissions regulate NSP-Wisconsin. NSP-Wisconsin is subject to rate regulation by state utility regulatory agencies, which have jurisdiction with respect to the rates of electric and natural gas distribution companies in Wisconsin and Michigan.

Rates are designed to recover plant investment, operating costs and an allowed return on investment. NSP-Wisconsin requests changes in rates for utility services through filings with governing commissions. Changes in operating costs can affect NSP-Wisconsin’s financial results, depending on the timing of rate case filings and implementation of final rates. Other factors affecting rate filings are new investments, sales, conservation and DSM efforts, and the cost of capital. In addition, the regulatory commissions authorize the ROE, capital structure and depreciation rates in rate proceedings. Decisions by these regulators can significantly impact NSP-Wisconsin’s results of operations.

See Rate Matters within Note 10 to the consolidated financial statements for further information.

Summary of Regulatory Agencies / RTO and Areas of Jurisdiction

Regulatory Body / RTO	Additional Information on Regulatory Authority
PSCW	Retail rates, services and other aspects of electric and natural gas operations. Certifies the need for new generating plants and electric transmission lines before the facilities may be sited and built. The PSCW has a biennial base rate filing requirement. By June of each odd numbered year, NSP-Wisconsin must submit a rate filing for the test year beginning the following January. Pipeline safety compliance.
MPSC	Retail rates, services and other aspects of electric and natural gas operations. Certifies the need for new generating plants and electric transmission lines before the facilities may be sited and built. Pipeline safety compliance.
FERC	Wholesale electric operations, hydroelectric generation licensing, accounting practices, wholesale sales for resale, transmission of electricity in interstate commerce, compliance with NERC electric reliability standards, asset transactions and mergers and natural gas transactions in interstate commerce.
MISO	NSP-Wisconsin is a transmission owning member of the MISO RTO that operates within the MISO RTO and wholesale energy market. NSP-Wisconsin and NSP-Minnesota are jointly authorized by the FERC to make wholesale electric sales at market-based prices.
DOT	Pipeline safety compliance.

Recovery Mechanisms

Mechanism	Additional Information
Annual Fuel Cost Plan	NSP-Wisconsin does not have an automatic electric fuel adjustment clause. Under Wisconsin rules, utilities submit a forward-looking annual fuel cost plan to the PSCW. Once the PSCW approves the plan, utilities defer the amount of any fuel cost under-recovery or over-recovery in excess of a 2% annual tolerance band, for future rate recovery or refund. Approval of a fuel cost plan and any rate adjustment for refund or recovery of deferred costs is determined by the PSCW. Rate recovery of deferred fuel cost is subject to an earnings test based on the most recently authorized ROE. Under-collections that exceed the 2% annual tolerance band may not be recovered if the utility earnings for that year exceed the authorized ROE.
Power Supply Cost Recovery Factors	NSP-Wisconsin’s retail electric rate schedules for Michigan customers include power supply cost recovery factors, based on 12-month projections. After each 12-month period, a reconciliation is submitted whereby over-recoveries are refunded and any under-recoveries are collected from customers.
Wisconsin Energy Efficiency Program	The primary energy efficiency program is funded by the utilities, but operated by independent contractors subject to oversight by the PSCW and utilities. NSP-Wisconsin recovers these costs from customers.
PGA	NSP-Wisconsin has a retail PGA cost-recovery mechanism for Wisconsin to recover the actual cost of natural gas and transportation and storage services.
Natural Gas Cost-Recovery Factor (MI)	NSP-Wisconsin’s natural gas rates for Michigan customers include a natural gas cost-recovery factor, based on 12-month projections and trued-up to actual amounts on an annual basis.

Pending and Recently Concluded Regulatory Proceedings

2021 Electric Fuel Cost Recovery — In December 2020, the PSCW approved the NSP-Wisconsin application to update its 2021 fuel cost and decrease retail electric rates for 2021 by approximately $12 million.

Request to Participate in Utility Money Pool — In October 2020, the PSCW approved NSP-Wisconsin’s application to participate in the Money Pool.

NSP-Wisconsin Solar Proposal — In October 2020, NSP-Wisconsin filed for a 74 MW solar facility build-own-transfer in Wisconsin for approximately $100 million. A PSCW decision is expected in the third quarter of 2021.

Purchased Power and Transmission Services

The NSP System expects to use power plants, power purchases, conservation and DSM options, new generation facilities and expansion of power plants to meet its system capacity requirements.

Purchased Power — Through the Interchange Agreement, NSP-Wisconsin receives power purchased by NSP-Minnesota from other utilities and independent power producers. Long-term purchased power contracts for dispatchable resources typically require a capacity charge and an energy charge. NSP-Minnesota makes short-term purchases to meet system requirements, replace company owned generation, meet operating reserve obligations or obtain energy at a lower cost.

Purchased Transmission Services — NSP-Minnesota and NSP-Wisconsin have contracts with MISO and other regional transmission service providers to deliver power and energy to their customers.

Wholesale and Commodity Marketing Operations

NSP-Wisconsin does not serve any wholesale requirements customers at cost-based regulated rates.

17

ITEM 7A — QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Derivatives, Risk Management and Market Risk

NSP-Wisconsin is exposed to a variety of market risks in the normal course of business. Market risk is the potential loss that may occur as a result of adverse changes in the market or fair value of a particular instrument or commodity. All financial and commodity-related instruments, including derivatives, are subject to market risk. 

See Note 8 to the consolidated financial statements for further information.

NSP-Wisconsin is exposed to the impact of adverse changes in price for energy and energy-related products, which is partially mitigated by the use of commodity derivatives. In addition to ongoing monitoring and maintaining credit policies intended to minimize overall credit risk, management takes steps to mitigate changes in credit and concentration risks associated with its derivatives and other contracts, including parental guarantees and requests of collateral. While NSP-Wisconsin expects that the counterparties will perform under the contracts underlying its derivatives, the contracts expose NSP-Wisconsin to certain credit and non-performance risk.

Distress in the financial markets may impact counterparty risk, the fair value of the securities in the pension fund and NSP-Wisconsin’s ability to earn a return on short-term investments.

Commodity Price Risk — NSP-Wisconsin is exposed to commodity price risk in its electric and natural gas operations. Commodity price risk is managed by entering into long- and short-term physical purchase and sales contracts for natural gas used in distribution activities. Commodity price risk is also managed through the use of financial derivative instruments. NSP-Wisconsin’s risk management policy allows it to manage commodity price risk within each rate-regulated operation per commission approved hedge plans.

Interest Rate Risk — NSP-Wisconsin is subject to interest rate risk. NSP-Wisconsin’s risk management policy allows interest rate risk to be managed through the use of fixed rate debt, floating rate debt and interest rate derivatives such as swaps, caps, collars and put or call options.

A 100 basis point change in the benchmark rate on NSP-Wisconsin’s variable rate debt would impact pretax interest expense annually by an immaterial amount and $1 million for the year ended Dec. 31, 2020 and 2019, respectively.

Credit Risk — NSP-Wisconsin is also exposed to credit risk. Credit risk relates to the risk of loss resulting from counterparties’ nonperformance on their contractual obligations. NSP-Wisconsin maintains credit policies intended to minimize overall credit risk and actively monitor these policies to reflect changes and scope of operations.

At Dec. 31, 2020 and 2019, a 10% increase or decrease in commodity prices would have no impact on credit exposure.

NSP-Wisconsin conducts credit reviews for all counterparties and employs credit risk controls, such as letters of credit, parental guarantees, master netting agreements and termination provisions. Credit exposure is monitored and, when necessary, the activity with a specific counterparty is limited until credit enhancement is provided. Distress in the financial markets could increase NSP-Wisconsin credit risk.

See Note 8 to the consolidated financial statements for further information.

Natural Gas Fuel and Electricity Purchases

In February 2021, the United States experienced winter storm Uri and extreme cold temperatures in the central United States. This severe weather event increased the demand for natural gas used in our electric and natural gas businesses. Certain operational assets were impacted by extreme cold temperatures and the cold further impacted the availability of renewable generation across the region (which typically acts as a hedge against commodity prices) contributing to extremely high market prices for natural gas and electricity. As a result, electric and natural gas fuel costs increased approximately $45 million. These amounts are preliminary estimates through Feb. 16, 2021 and are subject to final settlement.

NSP-Wisconsin has fuel recovery mechanisms in all of its states to recover the increased cost of natural gas and electricity. However, given the impact of these higher costs to our customers during a pandemic, we expect our regulators to undertake a heightened review and we intend to work with our commissions to recover these costs over time to help mitigate the impacts on customer bills. NSP-Wisconsin is taking action to increase planned debt issuances to ensure adequate liquidity for the timing difference between fuel payments and revenue collection from customers and to address any potential need to post collateral.

ITEM 8 — FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

See Item 15-1 for an index of financial statements included herein.

See Note 13 to the consolidated financial statements for further information.

18

Management Report on Internal Control Over Financial Reporting

The management of NSP-Wisconsin is responsible for establishing and maintaining adequate internal control over financial reporting. NSP-Wisconsin’s internal control system was designed to provide reasonable assurance to Xcel Energy Inc.’s and NSP-Wisconsin’s management and board of directors regarding the preparation and fair presentation of published financial statements.

All internal control systems, no matter how well designed, have inherent limitations. Therefore, even those systems determined to be effective can provide only reasonable assurance with respect to financial statement preparation and presentation.

NSP-Wisconsin management assessed the effectiveness of NSP-Wisconsin’s internal control over financial reporting as of Dec. 31, 2020. In making this assessment, it used the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) in Internal Control — Integrated Framework (2013). Based on our assessment, we believe that, as of Dec. 31, 2020, NSP-Wisconsin’s internal control over financial reporting is effective at the reasonable assurance level based on those criteria.

/s/ BEN FOWKE	/s/ BRIAN J. VAN ABEL
Ben Fowke	Brian J. Van Abel
Chairman, Chief Executive Officer and Director	Executive Vice President, Chief Financial Officer and Director
Feb. 17, 2021	Feb. 17, 2021

19

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the stockholder and Board of Directors of Northern States Power Company, a Wisconsin corporation

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Northern States Power Company, a Wisconsin corporation and subsidiaries (the "Company") as of December 31, 2020 and 2019, the related consolidated statements of income, comprehensive income, cash flows and common stockholder's equity, for each of the three years in the period ended December 31, 2020, and the related notes and the schedule listed in the Index at Item 15 (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2020 and 2019 , and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2020, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Regulatory Assets and Liabilities - Impact of Rate Regulation on the Financial Statements — Refer to Notes 4 and 10 to the consolidated financial statements.

Critical Audit Matter Description

The Company is subject to rate regulation by state utility regulatory agencies, which have jurisdiction with respect to the rates of electric and natural gas distribution companies in Wisconsin and Michigan. The Company is also subject to the jurisdiction of the Federal Energy Regulatory Commission for its wholesale electric operations, hydroelectric generation licensing, accounting practices, wholesale sales for resale, transmission of electricity in interstate commerce, compliance with North American Electric Reliability Corporation standards, asset transactions and mergers and natural gas transactions in interstate commerce, (collectively with state utility regulatory agencies, the “Commissions”). Management has determined it meets the requirements under accounting principles generally accepted in the United States of America to prepare its financial statements applying the specialized rules to account for the effects of cost-based rate regulation. Accounting for the economics of rate regulation affects multiple financial statement line items and disclosures, including property, plant and equipment, regulatory assets and liabilities, operating revenues and expenses, and income taxes.

The Company is subject to regulatory rate setting processes. Rates are determined and approved in regulatory proceedings based on an analysis of the Company’s costs to provide utility service and a return on, and recovery of, the Company’s investment in assets required to deliver services to customers. Accounting for the Company’s regulated operations provides that rate-regulated entities report assets and liabilities consistent with the recovery of those incurred costs in rates, if it is probable that such rates will be charged and collected. The Commissions’ regulation of rates is premised on the full recovery of incurred costs and a reasonable rate of return on invested capital. Decisions by the Commissions in the future will impact the accounting for regulated operations, including decisions about the amount of allowable costs and return on invested capital included in rates and any refunds that may be required. In the rate setting process, the Company’s rates result in the recording of regulatory assets and liabilities based on the probability of future cash flows. Regulatory assets generally represent incurred or accrued costs that have been deferred because future recovery from customers is probable. Regulatory liabilities generally represent amounts that are expected to be refunded to customers in future rates or amounts collected in current rates for future costs.

20

We identified the impact of rate regulation as a critical audit matter due to the significant judgments made by management to support its assertions about impacted account balances and disclosures and the high degree of subjectivity involved in assessing the impact of future regulatory orders on the financial statements. Management judgments include assessing the likelihood of (1) recovery in future rates of incurred costs, (2) a disallowance of part of the cost of recently completed plant, and 3) a refund due to customers. Given that management’s accounting judgments are based on assumptions about the outcome of future decisions by the Commissions, auditing these judgments required specialized knowledge of accounting for rate regulation and the rate setting process due to its inherent complexities.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to the uncertainty of future decisions by the Commissions included the following, among others:

•We tested the effectiveness of management’s controls over the evaluation of the likelihood of (1) the recovery in future rates of costs deferred as regulatory assets, and (2) a refund or a future reduction in rates that should be reported as regulatory liabilities. We also tested the effectiveness of management’s controls over the recognition of regulatory assets or liabilities and the monitoring and evaluation of regulatory developments that may affect the likelihood of recovering costs in future rates or of a future reduction in rates.

•We evaluated the Company’s disclosures related to the impacts of rate regulation, including the balances recorded and regulatory developments.

•We read relevant regulatory orders issued by the Commissions for the Company, regulatory statutes, interpretations, procedural memorandums, filings made by intervenors, and other publicly available information to assess the likelihood of recovery in future rates or of a future reduction in rates based on precedents of the Commissions’ treatment of similar costs under similar circumstances. We also evaluated regulatory filings for any evidence that intervenors are challenging full recovery of the cost of any capital projects. If the full recovery of project costs is being challenged by intervenors, we evaluated management’s assessment of the probability of a disallowance. We evaluated the external information and compared to the Company’s recorded regulatory assets and liabilities for completeness.

•We obtained management’s analysis and correspondence from counsel, as appropriate, regarding regulatory assets or liabilities not yet addressed in a regulatory order to assess management’s assertion that amounts are probable of recovery or a future reduction in rates.

/s/ DELOITTE & TOUCHE LLP

Minneapolis, Minnesota

February 17, 2021

We have served as the Company’s auditor since 2002.

21

NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

(amounts in millions)

	Year Ended Dec. 31
	2020		2019		2018
Operating revenues
Electric, non-affiliates	$	687	$	668	$	721
Electric, affiliates	168		177		158
Natural gas	119		136		142
Other	—		—		1
Total operating revenues	974		981		1,022
Operating expenses
Electric fuel and purchased power, non-affiliates	13		11		13
Purchased power, affiliates	379		394		411
Cost of natural gas sold and transported	53		65		69
Operating and maintenance expenses	191		201		203
Conservation program expenses	13		12		12
Depreciation and amortization	156		138		126
Taxes (other than income taxes)	28		29		29
Total operating expenses	833		850		863
Operating income	141		131		159
Other expense, net	(8)		(1)		(3)
Allowance for funds used during construction — equity	5		3		9
Interest charges and financing costs
Interest charges — includes other financing costs of $1, $1 and $2, respectively	40		39		39
Allowance for funds used during construction — debt	(2)		(1)		(4)
Total interest charges and financing costs	38		38		35
Income before income taxes	100		95		130
Income tax (benefit) expense	(7)		16		32
Net income	$	107	$	79	$	98

See Notes to Consolidated Financial Statements

22

NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

(amounts in millions)

	Year Ended Dec. 31
	2020		2019		2018
Operating activities
Net income	$	107	$	79	$	98
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	158		139		128
Deferred income taxes	(36)		5		23
Allowance for equity funds used during construction	(5)		(3)		(9)
Provision for bad debts	7		7		4
Changes in operating assets and liabilities:
Accounts receivable	(12)		(10)		(5)
Accrued unbilled revenues	—		3		4
Inventories	(5)		(8)		(8)
Other current assets	(3)		13		2
Accounts payable	(3)		(10)		(9)
Net regulatory assets and liabilities	—		15		(20)
Other current liabilities	4		11		(13)
Pension and other employee benefit obligations	(7)		(7)		(15)
Other, net	(3)		—		3
Net cash provided by operating activities	202		234		183
Investing activities
Capital/construction expenditures	(238)		(212)		(226)
Net cash used in investing activities	(238)		(212)		(226)
Financing activities
(Repayments of) proceeds from short-term borrowings, net	(46)		13		40
Proceeds from issuance of long-term debt	97		—		197
Repayments of long-term debt	—		—		(151)
Capital contributions from parent	56		48		49
Dividends paid to parent	(70)		(84)		(91)
Net cash provided by (used in) financing activities	37		(23)		44
Net change in cash, cash equivalents and restricted cash	1		(1)		1
Cash, cash equivalents and restricted cash at beginning of period	1		2		1
Cash, cash equivalents and restricted cash at end of period	$	2	$	1	$	2
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	$	(36)	$	(36)	$	(33)
Cash paid for income taxes, net	(26)		—		(21)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	$	21	$	29	$	32
Inventory transfers to property, plant and equipment	5		9		8
Allowance for equity funds used during construction	5		3		9

See Notes to Consolidated Financial Statements

23

NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(amounts in millions, except share and per share data)

	Dec. 31
	2020		2019
Assets
Current assets
Cash and cash equivalents	$	2	$	1
Accounts receivable, net	70		59
Accrued unbilled revenues	53		53
Other receivables	1		—
Inventories	15		16
Regulatory assets	19		72
Prepaid taxes	24		23
Prepayments and other	7		5
Total current assets	191		229
Property, plant and equipment, net	2,484		2,359
Other assets
Regulatory assets	215		224
Other investments	3		3
Other	1		1
Total other assets	219		228
Total assets	$	2,894	$	2,816
Liabilities and Equity
Current liabilities
Current portion of long-term debt	$	19	$	—
Short-term debt	19		65
Accounts payable	41		54
Accounts payable to affiliates	15		19
Dividends payable to parent	19		15
Regulatory liabilities	31		79
Taxes accrued	12		7
Environmental liabilities	4		6
Accrued interest	10		9
Other	15		20
Total current liabilities	185		274
Deferred credits and other liabilities
Deferred income taxes	307		298
Deferred investment tax credits	6		7
Regulatory liabilities	350		371
Environmental liabilities	16		18
Customer advances	20		19
Pension and employee benefit obligations	28		33
Other	27		21
Total deferred credits and other liabilities	754		767
Commitments and contingencies
Capitalization
Long-term debt	887		808
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares      outstanding at Dec. 31, 2020 and Dec. 31, 2019, respectively	93		93
Additional paid in capital	605		537
Retained earnings	370		337
Total common stockholder's equity	1,068		967
Total liabilities and equity	$	2,894	$	2,816

See Notes to Consolidated Financial Statements

24

NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER’S EQUITY

(amounts in millions, except share data)

	Common Stock							Total Common Stockholder’s Equity
	Shares	Par Value		Additional Paid In Capital		Retained Earnings
Balance at Dec. 31, 2017	933,000	$	93	$	449	$	334	$	876
Net income						98		98
Common dividends declared to parent						(93)		(93)
Contribution of capital by parent				61				61
Balance at Dec. 31, 2018	933,000	$	93	$	510	$	339	$	942
Net income						79		79
Common dividends declared to parent						(81)		(81)
Contribution of capital by parent				27				27
Balance at Dec. 31, 2019	933,000	$	93	$	537	$	337	$	967
Net income						107		107
Common dividends declared to parent						(74)		(74)
Contribution of capital by parent				68				68
Balance at Dec. 31, 2020	933,000	$	93	$	605	$	370	$	1,068

See Notes to Consolidated Financial Statements

25

Notes to Consolidated Financial Statements

1. Summary of Significant Accounting Policies

General — NSP-Wisconsin is engaged in the regulated generation, transmission, distribution and sale of electricity and in the regulated purchase, transportation, distribution and sale of natural gas.

NSP-Wisconsin’s consolidated financial statements include its wholly-owned subsidiaries and VIEs for which it is the primary beneficiary. In the consolidation process, all intercompany transactions and balances are eliminated. NSP-Wisconsin has investments in certain transmission facilities jointly owned with nonaffiliated utilities.

NSP-Wisconsin’s proportionate share of jointly owned facilities is recorded as property, plant and equipment on the consolidated balance sheets and NSP-Wisconsin’s proportionate share of the operating costs associated with these facilities is included in its consolidated statements of income.

NSP-Wisconsin’s consolidated financial statements are presented in accordance with GAAP. All of NSP-Wisconsin’s underlying accounting records also conform to the FERC uniform system of accounts or to systems required by various state regulatory commissions. Certain amounts in the consolidated financial statements or notes have been reclassified for comparative purposes; however, such reclassifications did not affect net income, total assets, liabilities, equity or cash flows.

NSP-Wisconsin has evaluated events occurring after Dec. 31, 2020 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation.

Use of Estimates — NSP-Wisconsin uses estimates based on the best information available in recording transactions and balances resulting from business operations. Estimates are used on items such as plant depreciable lives or potential disallowances, AROs, certain regulatory assets and liabilities, tax provisions, uncollectible amounts, environmental costs, unbilled revenues, jurisdictional fuel and energy cost allocations and actuarially determined benefit costs. Recorded estimates are revised when better information becomes available or actual amounts can be determined. Revisions can affect operating results.

Regulatory Accounting — NSP-Wisconsin accounts for income and expense items in accordance with accounting guidance for regulated operations. Under this guidance:

•Certain costs, which would otherwise be charged to expense or other comprehensive income, are deferred as regulatory assets based on the expected ability to recover the costs in future rates.

•Certain credits, which would otherwise be reflected as income or other comprehensive income, are deferred as regulatory liabilities based on the expectation the amounts will be returned to customers in future rates or because the amounts were collected in rates prior to the costs being incurred.

Estimates of recovering deferred costs and returning deferred credits are based on specific ratemaking decisions or precedent for each item. Regulatory assets and liabilities are amortized consistent with the treatment in the rate setting process.

If changes in the regulatory environment occur, NSP-Wisconsin may no longer be eligible to apply this accounting treatment and may be required to eliminate regulatory assets and liabilities from its balance sheets. Such changes could have a material effect on NSP-Wisconsin’s results of operations, financial condition and cash flows.

See Note 4 for further information.

Income Taxes — NSP-Wisconsin accounts for income taxes using the asset and liability method, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. NSP-Wisconsin defers income taxes for all temporary differences between pretax financial and taxable income and between the book and tax bases of assets and liabilities. NSP-Wisconsin uses rates that are scheduled to be in effect when the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the period that includes the enactment date.

The effects of NSP-Wisconsin’s tax rate changes are generally subject to a normalization method of accounting. Therefore, the revaluation of most of its net deferred taxes upon a tax rate reduction results in the establishment of a net regulatory liability, which would be refundable to utility customers over the remaining life of the related assets. NSP-Wisconsin anticipates that a tax rate increase would result in the establishment of a regulatory asset, subject to regulatory approval.

Reversal of certain temporary differences are accounted for as current income tax expense due to the effects of past regulatory practices when deferred taxes were not required to be recorded due to the use of flow through accounting for ratemaking purposes. Tax credits are recorded when earned unless there is a requirement to defer the benefit and amortize it over the book depreciable lives of the related property. The requirement to defer and amortize tax credits only applies to federal ITCs related to public utility property. Utility rate regulation also has resulted in the recognition of regulatory assets and liabilities related to income taxes. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized.

NSP-Wisconsin follows the applicable accounting guidance to measure and disclose uncertain tax positions that it has taken or expects to take in its income tax returns. NSP-Wisconsin recognizes a tax position in its consolidated financial statements when it is more likely than not that the position will be sustained upon examination based on the technical merits of the position. Recognition of changes in uncertain tax positions are reflected as a component of income tax expense.

NSP-Wisconsin reports interest and penalties related to income taxes within other (expense) income or interest charges in the consolidated statements of income.

Xcel Energy Inc. and its subsidiaries, including NSP-Wisconsin, file consolidated federal income tax returns as well as consolidated or separate state income tax returns. Federal income taxes paid by Xcel Energy Inc. are allocated to its subsidiaries based on separate company computations. A similar allocation is made for state income taxes paid by Xcel Energy Inc. in connection with consolidated state filings. Xcel Energy Inc. also allocates its own income tax benefits to its direct subsidiaries.

See Note 7 for further information.

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Property, Plant and Equipment and Depreciation in Regulated Operations — Property, plant and equipment is stated at original cost. The cost of plant includes direct labor and materials, contracted work, overhead costs and AFUDC. The cost of plant retired is charged to accumulated depreciation and amortization. Amounts recovered in rates for future removal costs are recorded as regulatory liabilities. Significant additions or improvements extending asset lives are capitalized, while repairs and maintenance costs are charged to expense as incurred. Maintenance and replacement of items determined to be less than a unit of property are charged to operating expenses as incurred. Planned maintenance activities are charged to operating expense unless the cost represents the acquisition of an additional unit of property or the replacement of an existing unit of property.

Property, plant and equipment is tested for impairment when it is determined that the carrying value of the assets may not be recoverable. A loss is recognized in the current period if it becomes probable that part of a cost of a plant under construction or recently completed plant will be disallowed for recovery from customers and a reasonable estimate of the disallowance can be made. For investments in property, plant and equipment that are abandoned and not expected to go into service, incurred costs and related deferred tax amounts are compared to the discounted estimated future rate recovery, and a loss is recognized, if necessary.

NSP-Wisconsin records depreciation expense using the straight-line method over the plant’s useful life. Actuarial life studies are performed and submitted to the state and federal commissions for review. Upon acceptance by the various commissions, the resulting lives and net salvage rates are used to calculate depreciation. Plant removal costs are recovered in rates as authorized by the appropriate regulatory entities. The amount of removal costs are based on current factors used in existing depreciation rates. Depreciation expense, expressed as a percentage of average depreciable property, was approximately 3.6% in 2020, 3.6% in 2019 and 3.5% in 2018.

See Note 3 for further information.

AROs — NSP-Wisconsin accounts for AROs under accounting guidance that requires a liability for the fair value of an ARO to be recognized in the period in which it is incurred if it can be reasonably estimated, with the offsetting associated asset retirement costs capitalized as a long-lived asset. The liability is generally increased over time by applying the effective interest method of accretion, and the capitalized costs are depreciated over the useful life of the long-lived asset. Changes resulting from revisions to the timing or amount of expected asset retirement cash flows are recognized as an increase or a decrease in the ARO.

See Note 10 for further information.

Benefit Plans and Other Postretirement Benefits — NSP-Wisconsin maintains pension and postretirement benefit plans for eligible employees. Recognizing the cost of providing benefits and measuring the projected benefit obligation of these plans requires management to make various assumptions and estimates.

Certain unrecognized actuarial gains and losses and unrecognized prior service costs or credits are deferred as regulatory assets and liabilities, rather than recorded as other comprehensive income, based on regulatory recovery mechanisms.

See Note 9 for further information.

Environmental Costs — Environmental costs are recorded when it is probable NSP-Wisconsin is liable for remediation costs and the liability can be reasonably estimated. Costs are deferred as a regulatory asset if it is probable that the costs will be recovered from customers in future rates. Otherwise, the costs are expensed. If an environmental expense is related to facilities currently in use, such as emission-control equipment, the cost is capitalized and depreciated over the life of the plant.

Estimated remediation costs are regularly adjusted as estimates are revised and remediation proceeds. If other participating potentially responsible parties exist and acknowledge their potential involvement with a site, costs are estimated and recorded only for NSP-Wisconsin’s expected share of the cost.

Future costs of restoring sites are treated as a capitalized cost of plant retirement. The depreciation expense levels recoverable in rates include a provision for removal expenses. Removal costs recovered in rates before the related costs are incurred are classified as a regulatory liability.

See Note 10 for further information.

Revenue from Contracts with Customers — Performance obligations related to the sale of energy are satisfied as energy is delivered to customers. NSP-Wisconsin recognizes revenue that corresponds to the price of the energy delivered to the customer. The measurement of energy sales to customers is generally based on the reading of their meters, which occurs systematically throughout the month. At the end of each month, amounts of energy delivered to customers since the date of the last meter reading are estimated, and the corresponding unbilled revenue is recognized.

NSP-Wisconsin does not recognize a separate financing component of its collections from customers as contract terms are short-term in nature. NSP-Wisconsin presents its revenues net of any excise or sales taxes or fees.

NSP-Wisconsin has various rate-adjustment mechanisms that provide for the recovery of natural gas, electric fuel and purchased energy costs. Cost-adjustment tariffs may increase or decrease the level of revenue collected from customers and are revised periodically for differences between the total amount collected under the clauses and the costs incurred. When applicable, fuel cost over-recoveries (the excess of fuel revenue billed to customers over fuel costs incurred) are deferred as regulatory liabilities and under-recoveries (the excess of fuel costs incurred over fuel revenues billed to customers) are deferred as regulatory assets. NSP-Wisconsin must submit a forward looking fuel cost plan annually for approval by the PSCW. The rules also allow for deferral of any under-recovery or over-recovery of fuel costs in excess of a 2% annual tolerance band, for future rate recovery or refund, subject to PSCW approval.

Cash and Cash Equivalents — NSP-Wisconsin considers investments in instruments with a remaining maturity of three months or less at the time of purchase to be cash equivalents.

Accounts Receivable and Allowance for Bad Debts — Accounts receivable are stated at the actual billed amount net of an allowance for bad debts. NSP-Wisconsin establishes an allowance for uncollectible receivables based on a policy that reflects its expected exposure to the credit risk of customers.

As of Dec. 31, 2020 and 2019, the allowance for bad debts was $8 million and $6 million, respectively.

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Inventory — Inventory is recorded at average cost and consisted of the following:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Inventories
Materials and supplies	$	7	$	7
Fuel	4		4
Natural gas	4		5
Total inventories	$	15	$	16

Fair Value Measurements — NSP-Wisconsin presents cash equivalents, interest rate derivatives and commodity derivatives at estimated fair values in its consolidated financial statements. Cash equivalents are recorded at cost plus accrued interest; money market funds are measured using quoted NAVs. For interest rate derivatives, quoted prices based primarily on observable market interest rate curves are used to establish fair value. For commodity derivatives, the most observable inputs available are generally used to determine the fair value of each contract. In the absence of a quoted price, NSP-Wisconsin may use quoted prices for similar contracts or internally prepared valuation models to determine fair value.

For the pension and postretirement plan assets published trading data and pricing models, generally using the most observable inputs available, are utilized to estimate fair value for each security.

See Notes 8 and 9 for further information.

Derivative Instruments — NSP-Wisconsin uses derivative instruments in connection with its utility commodity price and interest rate activities, including forward contracts, futures, swaps and options. Any derivative instruments not qualifying for the normal purchases and normal sales exception are recorded on the consolidated balance sheets at fair value as derivative instruments. Classification of changes in fair value for those derivative instruments is dependent on the designation of a qualifying hedging relationship. Changes in fair value of derivative instruments not designated in a qualifying hedging relationship are reflected in current earnings or as a regulatory asset or liability. Classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

Interest rate hedging transactions are recorded as a component of interest expense. NSP-Wisconsin is allowed to recover in electric or natural gas rates the costs of certain financial instruments purchased to reduce commodity cost volatility.

Normal Purchases and Normal Sales — NSP-Wisconsin enters into contracts for purchases and sales of commodities for use in its operations. At inception, contracts are evaluated to determine whether a derivative exists and/or whether an instrument may be exempted from derivative accounting if designated as a normal purchase or normal sale.

See Note 8 for further information.

Other Utility Items

AFUDC — AFUDC represents the cost of capital used to finance utility construction activity. AFUDC is computed by applying a composite financing rate to qualified CWIP. The amount of AFUDC capitalized as a utility construction cost is credited to other nonoperating income (for equity capital) and interest charges (for debt capital). AFUDC amounts capitalized are included in NSP-Wisconsin’s rate base for establishing utility rates.

Alternative Revenue — Certain rate rider mechanisms qualify as alternative revenue programs. These mechanisms arise from costs imposed upon the utility by action of a regulator or legislative body related to an environmental, public safety or other mandate. When certain criteria are met, including expected collection within 24 months, revenue is recognized equal to the revenue requirement, which may include return on rate base items and incentives. The mechanisms are revised periodically for differences between total amount collected and the revenue recognized, which may increase or decrease the level of revenue collected from customers. Alternative revenues arising from these programs are presented on a gross basis and disclosed separately from revenue from contracts with customers.

See Note 6 for further information.

Conservation Programs — NSP-Wisconsin participates in and funds conservation programs in its retail jurisdictions to assist customers in conserving energy and reducing peak demand on the electric and natural gas systems. NSP-Wisconsin recovers approved conservation program costs in base rate revenue.

For operations in the state of Wisconsin, NSP-Wisconsin is required to contribute 1.2% of its three-year average annual operating revenues to the statewide energy efficiency and renewable resource program Focus on Energy. Funding is collected through base rates, and there is no financial incentive provided to the utility. The PSCW has full oversight of Focus on Energy including auditing and verification of programs. The program portfolio is outsourced to a third-party administrator who subcontracts as necessary to implement programs.

Emission Allowances — Emission allowances are recorded at cost, including broker commission fees. The inventory accounting model is utilized for all emission allowances and sales of these allowances are included in electric revenues.

RECs — Cost of RECs that are utilized for compliance is recorded as electric fuel and purchased power expense.

Sales of RECs are recorded in electric revenues on a gross basis. Cost of these RECs are recorded in electric fuel and purchased power expense.

2. Accounting Pronouncements

Recently Adopted

Credit Losses — In 2016, the FASB issued Financial Instruments - Credit Losses, Topic 326 (ASC Topic 326), which changes how entities account for losses on receivables and certain other assets. The guidance requires use of a current expected credit loss model, which may result in earlier recognition of credit losses than under previous accounting standards.

NSP-Wisconsin implemented the guidance using a modified-retrospective approach, recognizing an immaterial cumulative effect charge (after tax) to retained earnings on Jan 1. 2020. The Jan. 1, 2020 adoption of ASC Topic 326 did not have a significant impact on NSP-Wisconsin’s consolidated financial statements.

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3. Property, Plant, and Equipment

Major classes of property, plant and equipment

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Property, plant and equipment, net
Electric plant	$	3,197	$	3,025
Natural gas plant	391		365
Common and other property	221		201
CWIP	71		83
Total property, plant and equipment	3,880		3,674
Less accumulated depreciation	(1,396)		(1,315)
Property, plant and equipment, net	$	2,484	$	2,359

Joint Ownership of Transmission Facilities

Jointly owned assets as of Dec. 31, 2020:

(Millions of Dollars, Except Percent Owned)	Plant in Service		Accumulated Depreciation		CWIP		Percent Owned
Electric transmission:
La Crosse, WI to Madison, WI	$	188	$	12	$	—	37	%
CapX2020	169		23		—		80
Total	$	357	$	35	$	—

NSP-Wisconsin’s share of operating expenses and construction expenditures is included in the applicable utility accounts. Respective owners are responsible for providing their own financing.

4. Regulatory Assets and Liabilities

Regulatory assets and liabilities are created for amounts that regulators may allow to be collected or may require to be paid back to customers in future electric and natural gas rates. NSP-Wisconsin would be required to recognize the write-off of regulatory assets and liabilities in net income or other comprehensive income if changes in the utility industry no longer allow for the application of regulatory accounting guidance under GAAP.

Components of regulatory assets:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2020				Dec. 31, 2019
Regulatory Assets			Current		Noncurrent		Current		Noncurrent
Environmental remediation costs	1, 10	Various	$	13	$	94	$	35	$	108
Pension and retiree medical obligations	9	Various	4		67		12		70
State commission adjustments		Plant lives	1		20		1		19
Recoverable deferred taxes on AFUDC		Plant lives	—		18		—		17
Losses on reacquired debt		Term of related debt	—		2		—		2
Excess deferred taxes — TCJA	7	Various	—		—		23		—
Other		Various	1		14		1		8
Total regulatory assets			$	19	$	215	$	72	$	224

Components of regulatory liabilities:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2020				Dec. 31, 2019
Regulatory Liabilities			Current		Noncurrent		Current		Noncurrent
Plant removal costs	1, 10	Various	$	—	$	184	$	—	$	171
Deferred income tax adjustments and TCJA refunds (a)	7	Various	—		161		51		196
Deferred electric production and natural gas costs		Less than one year	17		1		17		—
United States Department of Energy Settlement		Less than one year	12		—		10		—
Other		Various	2		4		1		4
Total regulatory liabilities			$	31	$	350	$	79	$	371

(a)    Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA.

At Dec. 31, 2020 and 2019, NSP-Wisconsin’s regulatory assets not earning a return primarily included the unfunded portion of pension and retiree medical obligations. In addition, at Dec. 31, 2020 and 2019, regulatory assets included $0 million and $7 million, respectively, of past expenditures not earning a return. Amount is related to funded pension obligations.

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5. Borrowings and Other Financing Instruments

Short Term Borrowings

Short-Term Debt — NSP-Wisconsin meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility.

Commercial paper outstanding for NSP-Wisconsin was as follows:

(Millions of Dollars, Except Interest Rates)	Three Months Ended Dec. 31, 2020			Year Ended
				2020			2019			2018
Borrowing limit	$	150		$	150		$	150		$	150
Amount outstanding at period end	19			19			65			51
Average amount outstanding	4			30			51			28
Maximum amount outstanding	24			95			93			103
Weighted average interest rate, computed on a daily basis	0.17		%	1.59		%	2.38		%	2.31		%
Weighted average interest rate at period end	0.17			0.17			1.97			2.89

Letters of Credit — NSP-Wisconsin may use letters of credit, typically with terms of one year, to provide financial guarantees for certain operating obligations. At Dec. 31, 2020 and 2019, there were no letters of credit outstanding.

Credit Facility — In order to use commercial paper programs to fulfill short-term funding needs, NSP-Wisconsin must have revolving credit facilities in place at least equal to the amount of their respective commercial paper borrowing limits and cannot issue commercial paper in an aggregate amount exceeding available capacity under these credit facilities. The lines of credit provide short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

Amended Credit Agreement — In June 2019, NSP-Wisconsin entered into an amended five-year credit agreement with a syndicate of banks. The amended credit agreements has substantially the same terms and conditions as the prior credit agreement with the exception of the maturity, which is June 2024.

Features of the credit facility:

Debt-to-Total Capitalization Ratio (a)				Amount Facility May Be Increased (millions)	Additional Periods for Which a One-Year Extension May Be Requested (b)
2020		2019
46	%	48	%	N/A	1

(a)    The credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%.

(b)    All extension requests are subject to majority bank group approval.

The credit facility has a cross-default provision that NSP-Wisconsin would be in default on borrowings under the facility if NSP-Wisconsin or any of its subsidiaries, whose total assets exceed 15% of NSP-Wisconsin’s consolidated total assets, default on certain indebtedness in an aggregate principal amount exceeding $75 million.

If NSP-Wisconsin does not comply with the covenant, an event of default may be declared, and if not remedied, any outstanding amounts due under the facility can be declared due by the lender. As of Dec. 31, 2020, NSP-Wisconsin was in compliance with all financial covenants.

NSP-Wisconsin had the following committed credit facility available as of Dec. 31, 2020 (in millions):

Credit Facility (a)		Drawn (b)		Available
$	150	$	19	$	131

(a)This credit facility matures in June 2024.

(b)Includes outstanding commercial paper.

All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. NSP-Wisconsin had no direct advances on the facility outstanding at Dec. 31, 2020 and 2019, respectively.

Other Short-Term Borrowings — Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, had an immaterial note payable to Xcel Energy Inc. at Dec. 31, 2020 and 2019, respectively.

Long-Term Borrowings and Other Financing Instruments

Generally, all property of NSP-Wisconsin is subject to the lien of its first mortgage indenture. Debt premiums, discounts and expenses are amortized over the life of the related debt. The premiums, discounts and expenses for refinanced debt are deferred and amortized over the life of new issuance.

Long-term debt obligations for NSP-Wisconsin as of Dec. 31 (millions of dollars):

Financing Instrument	Interest Rate		Maturity Date	2020		2019
City of La Crosse resource recovery bond	6.00	%	Nov 1, 2021	$	19	$	19
First mortgage bonds	3.30		June 15, 2024	100		100
First mortgage bonds	3.30		June 15, 2024	100		100
First mortgage bonds	6.38		Sept. 1, 2038	200		200
First mortgage bonds	3.70		Oct. 1, 2042	100		100
First mortgage bonds	3.75		Dec. 1, 2047	100		100
First mortgage bonds	4.20		Sept. 1, 2048	200		200
First mortgage bonds (a)	3.05		May 1, 2051	100		—
Unamortized discount				(4)		(3)
Unamortized debt issuance cost				(9)		(8)
Current maturities				(19)		—
Total long-term debt				$	887	$	808

(a)2020 financing.

Maturities of long-term debt:

(Millions of Dollars)
2021	$	19
2022	—
2023	—
2024	200
2025	—

Deferred Financing Costs — Deferred financing costs of approximately $9 million and $8 million, net of amortization, are presented as a deduction from the carrying amount of long-term debt at Dec. 31, 2020 and 2019, respectively. NSP-Wisconsin is amortizing these financing costs over the remaining maturity periods of the related debt.

Dividend Restrictions — NSP-Wisconsin’s dividends are subject to the FERC’s jurisdiction, which prohibits the payment of dividends out of capital accounts. Dividends are solely to be paid from retained earnings.

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NSP-Wisconsin’s state regulatory commission additionally imposes dividend limitations, which are more restrictive than those imposed by the FERC.

Requirements and actuals as of Dec. 31, 2020:

Equity to Total Capitalization Ratio Required Range			Equity to Total Capitalization Ratio Actual
Low		High	2020
52.5	%	N/A	52.8	%

Unrestricted Retained Earnings			Total Capitalization		Limit on Total Capitalization (a)
$	7	million	1,940	million	N/A

(a) NSP-Wisconsin cannot pay annual dividends in excess of forecasted levels if its average equity-to-total capitalization ratio falls below the commission authorized level.

6. Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Wisconsin’s operating revenues consisted of the following:

	Year Ended Dec. 31, 2020
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	258	$	64	$	322
C&I	411		49		460
Other	6		—		6
Total retail	675		113		788
Interchange	168		—		168
Other	—		4		4
Total revenue from contracts with customers	843		117		960
Alternative revenue and other	12		2		14
Total revenues	$	855	$	119	$	974

	Year Ended Dec. 31, 2019
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	240	$	73	$	313
C&I	409		57		466
Other	6		—		6
Total retail	655		130		785
Interchange	177		—		177
Other	1		4		5
Total revenue from contracts with customers	833		134		967
Alternative revenue and other	12		2		14
Total revenues	$	845	$	136	$	981

	Year Ended Dec. 31, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	255	$	73	$	—	$	328
C&I	444		62		—		506
Other	6		—		1		7
Total retail	705		135		1		841
Interchange	158		—		—		158
Other	4		5		—		9
Total revenue from contracts with customers	867		140		1		1,008
Alternative revenue and other	12		2		—		14
Total revenues	$	879	$	142	$	1	$	1,022

7. Income Taxes

Federal Tax Loss Carryback Claims — In 2020, Xcel Energy identified certain expenses related to tax years 2009 - 2011 that qualify for an extended carryback claim. NSP-Wisconsin is not expected to accrue any income tax expense related to this adjustment.

Federal Audit — NSP-Wisconsin is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. Statute of limitations applicable to Xcel Energy’s consolidated federal income tax returns expire as follows:

Tax Year(s)	Expiration
2014 - 2016	July 2021

Additionally, the statute of limitations related to the federal tax loss carryback claim referenced above has been extended. Xcel Energy has recognized its best estimate of income tax expense that will result from a final resolution of this issue; however, the outcome and timing of a resolution is unknown.

In 2017, the IRS concluded the audit of tax years 2012 and 2013 and proposed an adjustment that would impact Xcel Energy’s NOL and ETR. Xcel Energy file a protest with the IRS. In April 2020, Xcel Energy and Appeals reached an agreement and no material adjustments were required.

In 2018, the IRS began an audit of tax years 2014 - 2016. In July 2020, Xcel Energy and the IRS reached an agreement and the related benefit was recognized.

State Audits — NSP-Wisconsin is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of Dec. 31, 2020, NSP-Wisconsin’s earliest open tax year that is subject to examination by state taxing authorities under applicable statutes of limitations is 2014. In 2018, Wisconsin began an audit of tax years 2014 - 2016. As of Dec. 31, 2020 no material adjustments have been proposed.

Unrecognized Tax Benefits — Unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which the ultimate deductibility is highly certain, but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the ETR, but would accelerate the payment to the taxing authority to an earlier period.

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Unrecognized tax benefits — permanent vs. temporary:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Unrecognized tax benefit — Permanent tax positions	$	1	$	2
Unrecognized tax benefit — Temporary tax positions	1		1
Total unrecognized tax benefit	$	2	$	3

Changes in unrecognized tax benefits:

(Millions of Dollars)	2020		2019		2018
Balance at Jan. 1	$	3	$	3	$	2
Additions for tax positions of prior years	1		—		1
Reductions for tax positions of prior years	(2)		—		—
Balance at Dec. 31	$	2	$	3	$	3

Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
NOL and tax credit carryforwards	$	(2)	$	(2)

Net deferred tax liability associated with the unrecognized tax benefit amounts and related NOLs and tax credits carryforwards were $1 million for both Dec. 31, 2020 and Dec. 31, 2019.

As the IRS audits resume and state audits progress, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $1 million in the next 12 months.

Payable for interest related to unrecognized tax benefits is partially offset by the interest benefit associated with NOL and tax credit carryforwards. Payables for interest related to unrecognized tax benefits at Dec. 31, 2020, 2019 and 2018 were not material. No amounts were accrued for penalties related to unrecognized tax benefits as of Dec. 31, 2020, 2019 or 2018.

Other Income Tax Matters — NOL amounts represent the tax loss that is carried forward and tax credits represent the deferred tax asset. NOL and tax credit carryforwards as of Dec. 31 were as follows:

(Millions of Dollars)	2020		2019
Federal tax credit carryforwards	$	7	$	5
State NOL carryforward	2		2

Federal carryforward periods expire between 2031 and 2040 and state carryforward periods expire between 2031 and 2035.

Total income tax expense from operations differs from the amount computed by applying the statutory federal income tax rate to income before income tax expense.

Effective income tax rate for years ended Dec. 31:

	2020		2019 (a)		2018 (a)
Federal statutory rate	21.0	%	21.0	%	21.0	%
State income tax on pretax income, net of federal tax effect	6.2		6.2		6.2
Increases (decreases) in tax from:
Plant regulatory differences (b)	(19.3)		(5.2)		(1.5)
Amortization of excess nonplant deferred taxes	(12.6)		—		—
Other tax credits, net NOL & tax credit allowances	(1.5)		(1.8)		(0.8)
Change in unrecognized tax benefits	(0.8)		0.7		0.4
Reversal of prior regulatory differences	—		(3.6)		—
Other, net	—		(0.5)		(0.7)
Effective income tax rate	(7.0)	%	16.8	%	24.6	%

(a)Prior periods have been reclassified to conform to current year presentation.

(b)Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions.

Components of income tax expense for years ended Dec. 31:

(Millions of Dollars)	2020		2019		2018
Current federal tax expense	$	25	$	6	$	8
Current state tax expense	6		5		2
Current change in unrecognized tax (benefit) expense	(1)		1		—
Deferred federal tax (benefit) expense	(37)		3		16
Deferred state tax expense	1		2		7
Deferred ITCs	(1)		(1)		(1)
Total income tax (benefit) expense	$	(7)	$	16	$	32

Components of deferred income tax expense as of Dec. 31:

(Millions of Dollars)	2020		2019		2018
Deferred tax expense excluding items below	$	9	$	17	$	24
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities	(45)		(12)		(1)
Deferred tax (benefit) expense	$	(36)	$	5	$	23

Components of net deferred tax liability as of Dec. 31:

(Millions of Dollars)	2020		2019 (a)
Deferred tax liabilities:
Difference between book and tax bases of property	$	324	$	304
Regulatory assets	32		50
Pension expense	12		14
Other	9		7
Total deferred tax liabilities	$	377	$	375
Deferred tax assets:
Regulatory liabilities	$	41	$	47
Tax credit carryforward	8		5
Environmental remediation	6		6
Other employee benefits	4		4
Rate refund	4		9
Deferred ITCs	3		3
Other	4		3
Total deferred tax assets	$	70	$	77
Net deferred tax liability	$	307	$	298

(a) Prior periods have been reclassified to conform to current year presentation.

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8. Fair Value of Financial Assets and Liabilities

Fair Value Measurements

Accounting guidance for fair value measurements and disclosures provides a single definition of fair value and requires disclosures about assets and liabilities measured at fair value. A hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value is established by this guidance.

•Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are highly liquid and actively traded instruments with quoted prices.

•Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts, or priced with models using highly observable inputs.

•Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 are those valued with models requiring significant management judgment or estimation.

Specific valuation methods include:

Cash equivalents — The fair values of cash equivalents are generally based on cost plus accrued interest; money market funds are measured using quoted NAV.

Interest rate derivatives — The fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts.

Commodity derivatives — The methods used to measure the fair value of commodity derivative forwards and options utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. 

When contractual settlements relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable forecasts of forward prices and volatilities on a valuation is evaluated, and may result in Level 3 classification.

Derivative Instruments Fair Value Measurements

NSP-Wisconsin enters into derivative instruments, including forward contracts, futures, swaps and options, for trading purposes and to manage risk in connection with changes in interest rates and utility commodity prices.

Interest Rate Derivatives — NSP-Wisconsin may enter into various instruments that effectively fix the yield or price on a specified benchmark interest rate for an anticipated debt issuance for a specific period. These derivative instruments are generally designated as cash flow hedges for accounting purposes. As of Dec. 31, 2020 and 2019 there were no interest rate derivatives designated as cash flow hedges, respectively.

Commodity Derivatives — NSP-Wisconsin may enter into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations, as well as for trading purposes. This could include the purchase or sale of natural gas to generate electric energy and natural gas for resale.

Consideration of Credit Risk and Concentrations — NSP-Wisconsin continuously monitors the creditworthiness of counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. Impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented on the consolidated balance sheets.

Impact of Derivative Activities on Income — Changes in the fair value of natural gas commodity derivatives resulted in net losses of $1 million, for the years ended Dec. 31, 2020 and 2019, respectively and immaterial net losses for the year ended Dec. 31, 2018, recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

During the years ended Dec. 31, 2020 and 2019, $1 million of natural gas commodity derivatives settlement losses were recognized, respectively, and immaterial settlement gains for the year ended Dec. 31, 2018, were recognized subject to purchased natural gas cost recovery mechanisms, which result in reclassifications of derivative settlement gains and losses out of income to a regulatory asset or liability, as appropriate.

NSP-Wisconsin had no derivative instruments designated as fair value hedges during the years ended Dec. 31, 2020, 2019 and 2018.

Recurring Fair Value Measurements — NSP-Wisconsin’s derivative assets measured at fair value on a recurring basis were as follows:

	Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	1	$	—	$	1	$	—	$	1

(a)NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2020. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)Included in prepayments and other current assets balance of $7 million at Dec. 31, 2020 on the consolidated balance sheets.

	Dec. 31, 2019
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	1	$	—	$	1	$	—	$	1

(a)NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2019. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)Included in prepayments and other current assets balance of $5 million at Dec. 31, 2019 on the consolidated balance sheets.

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Fair Value of Long-Term Debt

As of Dec. 31, other financial instruments for which the carrying amount did not equal fair value:

	2020				2019
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	906	$	1,124	$	808	$	924

Fair value of NSP-Wisconsin’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of Dec. 31, 2020 and 2019, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

9. Benefit Plans and Other Postretirement Benefits

Pension and Postretirement Health Care Benefits

Xcel Energy, which includes NSP-Wisconsin, has several noncontributory, qualified, defined benefit pension plans that cover almost all employees. All newly hired or rehired employees participate under the Cash Balance formula, which is based on pay credits using a percentage of annual eligible pay and annual interest credits. The average annual interest crediting rates for these plans was 1.78, 2.74 and 3.57 percent in 2020, 2019, and 2018, respectively. Some employees may participate under legacy formulas such as the traditional final average pay or pension equity. Xcel Energy’s policy is to fully fund into an external trust the actuarially determined pension costs subject to the limitations of applicable employee benefit and tax laws.

In addition to the qualified pension plans, Xcel Energy maintains a SERP and a nonqualified pension plan. The SERP is maintained for certain executives who participated in the plan in 2008, when the SERP was closed to new participants. The nonqualified pension plan provides benefits for compensation that is in excess of the limits applicable to the qualified pension plans, with distributions funded by Xcel Energy’s consolidated operating cash flows. Obligations of the SERP and nonqualified plan as of Dec. 31, 2020 and 2019 were $43 million and $39 million, respectively, of which $1 million was attributable to NSP-Wisconsin in both years. Xcel

Energy recognized net benefit cost for the SERP and nonqualified plans of $6 million and $4 million in 2020 and 2019, respectively, of which amounts attributable to NSP-Wisconsin were immaterial.

Xcel Energy, which includes NSPW, bases the investment-return assumption on expected long-term performance for each of the asset classes in its pension and postretirement health care portfolios. For pension assets, Xcel Energy considers the historical returns achieved by its asset portfolio over the past 20 years or longer period, as well as the long-term projected return levels. Xcel Energy and NSP-Wisconsin continually review their pension assumptions.

Pension cost determination assumes a forecasted mix of investment types over the long-term.

•Investment returns in 2020 were above the assumed level of 7.10%.

•Investment returns in 2019 were below the assumed level of 7.10%.

•Investment returns in 2018 were above the assumed level of 7.10%.

•In 2021, NSP-Wisconsin’s expected investment-return assumption is 6.60%.

Pension plan and postretirement benefit assets are invested in a portfolio according to Xcel Energy’s return, liquidity and diversification objectives to provide a source of funding for plan obligations and minimize contributions to the plan, within appropriate levels of risk. The principal mechanism for achieving these objectives is the asset allocation given the long-term risk, return, correlation and liquidity characteristics of each particular asset class. There were no significant concentrations of risk in any industry, index, or entity. Market volatility can impact even well-diversified portfolios and significantly affect the return levels achieved by the assets in any year.

Xcel Energy’s ongoing investment strategy is based on plan-specific investment recommendations that seek to minimize potential investment and interest rate risk as a plan’s funded status increases over time. The investment recommendations result in a greater percentage of long-duration fixed income securities being allocated to specific plans having relatively higher funded status ratios and a greater percentage of growth assets being allocated to plans having relatively lower funded status ratios.

Plan Assets

For each of the fair value hierarchy levels, NSP-Wisconsin’s pension plan assets measured at fair value:

	Dec. 31, 2020 (a)										Dec. 31, 2019 (a)
(Millions of Dollars)	Level 1		Level 2		Level 3		Measured at NAV		Total		Level 1		Level 2		Level 3		Measured at NAV		Total
Cash equivalents	$	8	$	—	$	—	$	—	$	8	$	6	$	—	$	—	$	—	$	6
Commingled funds	57		—		—		44		101		55		—		—		41		96
Debt securities	—		26		—		—		26		—		24		—		—		24
Equity securities	4		—		—		—		4		3		—		—		—		3
Other	1		—		—		—		1		(5)		—		—		—		(5)
Total	$	70	$	26	$	—	$	44	$	140	$	59	$	24	$	—	$	41	$	124

(a)See Note 8 for further information on fair value measurement inputs and methods.

NSP-Wisconsin has immaterial postretirement benefit plan assets that were measured at fair value at Dec. 31, 2020 and 2019.

No assets were transferred in or out of Level 3 for 2020. Immaterial assets were transferred in or out of Level 3 for 2019.

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Funded Status — Benefit obligations for both pension and postretirement plans increased from Dec. 31, 2019 to Dec. 31, 2020, due primarily to decreases in discount rates used in actuarial valuations. Comparisons of the actuarially computed benefit obligation, changes in plan assets and funded status of the pension and postretirement health care plans for NSP-Wisconsin are as follows:

	Pension Benefits				Postretirement Benefits
(Millions of Dollars)	2020		2019		2020		2019
Change in Benefit Obligation:
Obligation at Jan. 1	$	144	$	140	$	13	$	13
Service cost	4		4		—		—
Interest cost	5		6		1		1
Actuarial loss	13		8		—		—
Benefit payments	(12)		(14)		(1)		(1)
Obligation at Dec. 31	$	154	$	144	$	13	$	13
Change in Fair Value of Plan Assets:
Fair value of plan assets at Jan. 1	$	124	$	110	$	—	$	—
Actual return on plan assets	21		21		—		—
Employer contributions	7		7		1		1
Benefit payments	(12)		(14)		(1)		(1)
Fair value of plan assets at Dec. 31	$	140	$	124	$	—	$	—
Funded status of plans at Dec. 31	$	(14)	$	(20)	$	(13)	$	(13)
Amounts recognized in the Consolidated Balance Sheet at Dec. 31:
Current liabilities	$	—	$	—	$	(1)	$	(1)
Noncurrent liabilities	(14)		(20)		(12)		(12)
Net amounts recognized	$	(14)	$	(20)	$	(13)	$	(13)

	Pension Benefits				Postretirement Benefits
Significant Assumptions Used to Measure Benefit Obligations:	2020		2019		2020		2019
Discount rate for year-end valuation	2.71	%	3.49	%	2.65	%	3.47	%
Expected average long-term increase in compensation level	3.75	%	3.75	%	N/A		N/A
Mortality table	Pri-2012		Pri-2012		Pri-2012		Pri-2012
Health care costs trend rate — initial: Pre-65	N/A		N/A		5.50	%	6.00	%
Health care costs trend rate — initial: Post-65	N/A		N/A		5.00	%	5.10	%
Ultimate trend assumption — initial: Pre-65	N/A		N/A		4.50	%	4.50	%
Ultimate trend assumption — initial: Post-65	N/A		N/A		4.50	%	4.50	%
Years until ultimate trend is reached	N/A		N/A		5		3

Accumulated benefit obligation for the pension plan was $141 million and $132 million as of Dec. 31, 2020 and 2019, respectively.

Net Periodic Benefit Cost (Credit) — Net periodic benefit cost (credit), other than the service cost component, is included in other expense in the consolidated statements of income.

Components of net periodic benefit cost (credit) and amounts recognized in other comprehensive income and regulatory assets and liabilities:

	Pension Benefits									Postretirement Benefits
(Millions of Dollars)	2020			2019			2018			2020			2019			2018
Service cost	$	4		$	4		$	5		$	—		$	—		$	—
Interest cost	5			6			5			1			1			1
Expected return on plan assets	(8)			(8)			(9)			—			—			—
Amortization of net loss	5			4			6			—			—			—
Settlement charge (a)	—			—			7			—			—			—
Net periodic pension cost	$	6		$	6		$	14		$	1		$	1		$	1
Effects of regulation	7			—			(3)			—			—			—
Net benefit cost recognized for financial reporting	$	13		$	6		$	11		$	1		$	1		$	1
Significant Assumptions Used to Measure Costs:
Discount rate	3.49		%	4.31		%	3.63		%	3.47		%	4.32		%	3.62		%
Expected average long-term increase in compensation level	3.75			3.75			3.75			—			—			—
Expected average long-term rate of return on assets	7.10			7.10			7.10			4.50			4.50			5.30

(a)A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2018, as a result of lump-sum distributions during the 2018 plan year, NSP-Wisconsin recorded a total pension settlement charge of $7 million in 2018, a total of $2 million of that amount was recorded in the income statement in 2018. There were no settlement charges recorded to the qualified pension plans in 2020 and 2019.

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	Pension Benefits				Postretirement Benefits
(Millions of Dollars)	2020		2019		2020		2019
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost:
Net loss	$	60	$	64	$	7	$	7
Prior service credit	—		—		(1)		(1)
Total	$	60	$	64	$	6	$	6
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates:
Current regulatory assets	$	4	$	4	$	—	$	—
Noncurrent regulatory assets	56		60		6		6
Total	$	60	$	64	$	6	$	6

Measurement date Dec. 31, 2020 Dec. 31, 2019 Dec. 31, 2020 Dec. 31, 2019

Cash Flows — Funding requirements can be impacted by changes to actuarial assumptions, actual asset levels and other calculations prescribed by the requirements of income tax and other pension-related regulations. Required contributions were made in 2018-2021 to meet minimum funding requirements.

Total voluntary and required pension funding contributions across all four of Xcel Energy’s pension plans were as follows:

•$125 million in January 2021, of which $5 million was attributable to NSP-Wisconsin.

•$150 million in 2020, of which $7 million was attributable to NSP-Wisconsin.

•$154 million in 2019, of which $7 million was attributable to NSP-Wisconsin.

•$150 million in 2018, of which $10 million was attributable to NSP-Wisconsin.

The postretirement health care plans have no funding requirements other than fulfilling benefit payment obligations, when claims are presented and approved. Additional cash funding requirements are prescribed by certain state and federal rate regulatory authorities. Xcel Energy’s voluntary postretirement funding contributions were as follows:

•$10 million in January 2021, of which $1 million is attributable to NSP-Wisconsin.

•$11 million in 2020, of which $1 million, was attributable to NSP-Wisconsin.

•$15 million in 2019, of which $1 million was attributable to NSP-Wisconsin.

•$11 million in 2018, of which an immaterial amount was attributable to NSP-Wisconsin.

Target asset allocations:

	Pension Benefits				Postretirement Benefits
	2020		2019		2020		2019
Domestic and international equity securities	35	%	37	%	15	%	15	%
Long-duration fixed income and interest rate swap securities	35		30		—		—
Short-to-intermediate fixed income securities	13		14		72		72
Alternative investments	15		17		9		9
Cash	2		2		4		4
Total	100	%	100	%	100	%	100	%

The asset allocations above reflect target allocations approved in the calendar year to take effect in the subsequent year

Plan Amendments — In 2019, the Pension Protection Act measurement concept was extended beyond 2019 for NSP bargaining terminations and retirements to Dec. 31, 2022.

In 2020 and 2018, there were no significant plan amendments made which affected the postretirement benefit obligation.

Projected Benefit Payments

NSP-Wisconsin’s projected benefit payments:

(Millions of Dollars)	Projected Pension Benefit Payments		Gross Projected Postretirement Health Care Benefit Payments		Expected Medicare Part D Subsidies		Net Projected Postretirement Health Care Benefit Payments
2021	$	13	$	1	$	—	$	1
2022	12		1		—		1
2023	12		1		—		1
2024	12		1		—		1
2025	12		1		—		1
2026-2030	57		3		—		3

Defined Contribution Plans

Xcel Energy, which includes NSP-Wisconsin, maintains 401(k) and other defined contribution plans that cover most employees. The expense to these plans for NSP-Wisconsin was approximately $2 million in 2020, 2019 and 2018.

Multiemployer Plans

NSP-Wisconsin contributes to several union multiemployer pension plans, none of which are individually significant. These plans provide pension benefits to certain union employees who may perform services for multiple employers and do not participate in the NSP-Wisconsin sponsored pension plans. Contributing to these types of plans creates risk that differs from providing benefits under NSP-Wisconsin sponsored plans, in that if another participating employer ceases to contribute to a multiemployer plan, additional unfunded obligations may need to be funded over time by remaining participating employers.

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10. Commitments and Contingencies

Legal

NSP-Wisconsin is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories.

In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss. For current proceedings not specifically reported, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Wisconsin’s financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.

Gas Trading Litigation — e prime is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing but has not engaged in natural gas trading or marketing activities since 2003. Multiple lawsuits involving multiple plaintiffs seeking monetary damages were commenced against e prime and its affiliates, including Xcel Energy, between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. Cases were all consolidated in the U.S. District Court in Nevada.

Two cases remain active which include an MDL matter consisting of a Colorado purported class (Breckenridge) and a Wisconsin purported class (Arandell Corp.).

Breckenridge/Colorado — In February 2019, the MDL panel remanded Breckenridge back to the U.S. District Court in Colorado. In December 2020, a settlement in principle was reached for approximately $3 million. The parties have sought and are awaiting court approval of settlement.

Arandell Corp. — In February 2019, the case was remanded back to the U.S. District Court in Wisconsin.

Xcel Energy has concluded that a loss is remote for the remaining lawsuit.

Rate Matters

MISO ROE Complaints — In November 2013 and February 2015, customer groups filed two ROE complaints against MISO TOs, which includes NSP-Minnesota and NSP-Wisconsin. The first complaint requested a reduction in base ROE transmission formula rates from 12.38% to 9.15% for the time period of Nov. 12, 2013 to Feb. 11, 2015, and removal of ROE adders (including those for RTO membership). The second complaint requested, for a subsequent time period, a base ROE reduction from 12.38% to 8.67%.

In September 2016, the FERC issued an order (Opinion No. 551) granting a 10.32% base ROE effective for the first complaint period of Nov. 12, 2013 to Feb. 11, 2015 and subsequent to the date of the order. The D.C Circuit subsequently vacated and remanded the FERC Opinion.

In November 2019, the FERC issued an order (Opinion No. 569), which set the MISO base ROE at 9.88%, effective Sept. 28, 2016 and for the first complaint period. The FERC also dismissed the second complaint. In December 2019, MISO TOs filed a request for rehearing regarding the new ROE methodology announced in Opinion No. 569. Customers also filed requests for rehearing claiming, among other points, that the FERC erred by dismissing the second complaint without refunds.

In May 2020, the FERC issued an order (Opinion No. 569-A) which granted rehearing in part to Opinion 569 and further refined the FERC’s ROE methodology, most significantly to incorporate the risk premium model (in addition to the discounted cash flow and capital asset pricing models), resulting in a new base ROE of 10.02%, effective Sept. 28, 2016 and for the first complaint period. The FERC also affirmed its decision in Opinion No. 569 to dismiss the second complaint.

In June 2020, various parties filed requests for rehearing of Opinion 569-A with the FERC. In November 2020, the FERC issued an order (Opinion No. 569-B) in response to the rehearing requests. The FERC corrected certain inputs to its ROE calculation model, did not change the ROE for the first MISO complaint period and upheld its decision to deny refunds for the second complaint period. Each 10 basis point reduction in the allowed base ROE for the first complaint and second complaint would reduce net income by $2 million and $1 million, respectively.

Various parties have filed petitions for review of Opinion Nos. 569, 569-A and 569-B at the D.C. Circuit. These appeals remain pending.

Environmental

New and changing federal and state environmental mandates can create financial liabilities for NSP-Wisconsin, which are normally recovered through the regulated rate process.

Site Remediation

Various federal and state environmental laws impose liability where hazardous substances or other regulated materials have been released to the environment. NSP-Wisconsin may sometimes pay all or a portion of the cost to remediate sites where past activities of NSP-Wisconsin’s predecessors or other parties have caused environmental contamination. Environmental contingencies could arise from various situations, including sites of former MGPs; and third-party sites, such as landfills, for which NSP-Wisconsin is alleged to have sent wastes to that site.

MGP, Landfill and Disposal Sites

Ashland MGP Site — NSP-Wisconsin was named a responsible party for contamination at the Ashland/Northern States Power Lakefront Superfund Site (the Site) in Ashland, Wisconsin. Remediation was completed in 2019 and restoration activities were completed in 2020. Groundwater treatment activities will continue for many years.

The cost estimate for remediation and restoration of the entire site is approximately $199 million. At Dec. 31, 2020 and 2019, NSP-Wisconsin had a total liability of $19 million and $23 million, respectively, for the entire site.

NSP-Wisconsin has deferred the unrecovered portion of the estimated Site remediation and restoration costs as a regulatory asset. The PSCW has authorized NSP-Wisconsin rate recovery for all remediation and restoration costs incurred at the Site and application of a 3% carrying charge to the regulatory asset.

In January 2021, the EPA confirmed that NSP-Wisconsin completed its work on the soils and sediments at the Site and all that remains is the long-term groundwater pump and treat program.

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In addition to the Ashland Site, NSP-Wisconsin is currently investigating, remediating or performing post-closure actions at one other MGP, landfill or other disposal site across its service territory.

NSP-Wisconsin has recognized its best estimate of costs/liabilities that will result from final resolution of these issues, however, the outcome and timing is unknown. In addition, there may be insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of costs incurred.

Environmental Requirements — Water and Waste

Federal CWA WOTUS Rule — In April 2020, the EPA and U.S. Army Corps of Engineers (“Agencies”) replaced the 2015 WOTUS rule and narrowed the definition of WOTUS (“2020 WOTUS Rule”). The new definition simplifies the process whether waters are subject to CWA jurisdiction and streamlines the permitting process. NSP-Wisconsin does not anticipate that compliance costs will be material.

Federal CWA Section 316(b) — The federal CWA requires the EPA to regulate cooling water intake structures to assure that these structures reflect the best technology available for minimizing impingement and entrainment of aquatic species. NSP-Wisconsin estimates the likely cost for complying with impingement requirements is approximately $4 million, to be incurred between 2021 and 2028, while the total cost of entrainment improvements is anticipated to be immaterial. NSP-Wisconsin believes two plants could be required to make improvements to reduce impingement and entrainment. The exact total cost of the impingement and entrainment improvements is uncertain but could be up to $4 million. NSP-Wisconsin anticipates these costs will be fully recoverable through regulatory mechanisms.

AROs — AROs have been recorded for NSP-Wisconsin’s assets.

NSP-Wisconsin’s AROs were as follows:

	2020
(Millions of Dollars)	Jan. 1, 2020		Cash Flow Revisions (a)		Dec. 31, 2020 (b)
Electric
Distribution	$	5	$	—	$	5
Steam, hydro and other production	4		4		8
Natural gas
Distribution	9		—		9
Total liability (c)	$	18	$	4	$	22

(a)In 2020, AROs were revised for changes in timing and estimates of cash flows. Revisions in steam, hydro and other production AROs primarily related to changes in cost estimates for remediation of ash containment facilities.

(b)There were no ARO amounts incurred or settled in 2020.

(c)Included in other long-term liabilities balance in the consolidated balance sheet.

	2019
(Millions of Dollars)	Jan. 1, 2019		Accretion		Cash Flow Revisions		Dec. 31, 2019 (a)
Electric
Distribution	$	5	$	—	$	—	$	5
Steam, hydro and other production	4		—		—		4
Natural gas
Distribution	9		1		(1)		9
Total liability (b)	$	18	$	1	$	(1)	$	18

(a)There were no ARO amounts incurred or settled in 2019.

(b)Included in other long-term liabilities balance in the consolidated balance sheet.

Indeterminate AROs — Outside of the recorded asbestos AROs, other plants or buildings may contain asbestos due to the age of many of NSP-Wisconsin’s facilities, but no confirmation or measurement of the cost of removal could be determined as of Dec. 31, 2020. Therefore, an ARO has not been recorded for these facilities.

Joint Operating System

The electric production and transmission system of NSP-Wisconsin is managed as the NSP System. The electric production and transmission costs of the entire NSP System are shared by NSP-Minnesota and NSP-Wisconsin. A FERC approved agreement between the two companies, called the Interchange Agreement, provides for the sharing of all costs of generation and transmission facilities of the system, including capital costs. Such costs include current and potential obligations of NSP-Minnesota related to its nuclear generating facilities.

NSP-Minnesota’s public liability for claims from any nuclear incident is limited to $13.8 billion under the Price-Anderson amendment to the Atomic Energy Act. NSP-Minnesota has secured $450 million of coverage for its public liability exposure with a pool of insurance companies. The remaining $13.3 billion of exposure is funded by the Secondary Financial Protection Program, available from assessments by the federal government.

NSP-Minnesota is subject to assessments of up to $138 million per reactor-incident for each of its three licensed reactors, for public liability arising from a nuclear incident at any licensed nuclear facility in the United States. The maximum funding requirement is $21 million per reactor-incident during any one year. Maximum assessments are subject to inflation adjustments by the NRC and state premium taxes. The NRC’s last adjustment was effective November 2018.

NSP-Minnesota purchases insurance for property damage and site decontamination cleanup costs from NEIL and EMANI. The coverage limits are $2.8 billion for each of NSP-Minnesota’s two nuclear plant sites. NEIL also provides business interruption insurance coverage up to $350 million, including the cost of replacement power during prolonged accidental outages of nuclear generating units. Premiums are expensed over the policy term.

All companies insured with NEIL are subject to retroactive premium adjustments if losses exceed accumulated reserve funds. Capital has been accumulated in the reserve funds of NEIL and EMANI to the extent that NSP-Minnesota would have no exposure for retroactive premium assessments in case of a single incident under the business interruption and the property damage insurance coverage. NSP-Minnesota could be subject to annual maximum assessments of approximately $11 million for business interruption insurance and $34 million for property damage insurance if losses exceed accumulated reserve funds.

Fuel Contracts

NSP-Wisconsin has entered into various long-term commitments for the purchase and delivery of a significant portion of its refuse-derived fuel/wood and natural gas requirements. These contracts expire between 2021 and 2029. NSP-Wisconsin is required to pay additional amounts depending on actual quantities shipped under these agreements.

As NSP-Wisconsin does not have an automatic electric fuel adjustment clause for Wisconsin retail customers, NSP-Wisconsin utilizes deferred accounting treatment for future rate recovery or refund when fuel costs differ from the amount included in rates by more than 2% on an annual basis, as determined by the PSCW after an opportunity for a hearing and an earnings test based on NSP-Wisconsin’s authorized ROE.

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Estimated minimum purchases under these contracts as of Dec. 31, 2020:

(Millions of Dollars)	Refuse-derived fuel/wood		Natural gas supply		Natural gas storage and transportation
2021	$	5	$	8	$	16
2022	1		—		14
2023	1		—		11
2024	1		—		9
2025	1		—		8
Thereafter	3		—		14
Total (a)	$	12	$	8	$	72

(a)Excludes additional amounts allocated to NSP-Wisconsin through intercompany charges.

Additional expenditures for fuel and natural gas storage and transportation will be required to meet expected future electric generation and natural gas needs.

VIEs

NSP-Wisconsin has entered into limited partnerships for the construction and operation of affordable rental housing developments, which qualify for low-income housing tax credits. NSP-Wisconsin has determined the low-income housing partnerships to be VIEs primarily due to contractual arrangements within each limited partnership that establishes sharing of ongoing voting control and profits and losses that do not align with the partners’ proportional equity ownership.

NSP-Wisconsin has the power to direct the activities that most significantly impact these entities’ economic performance. Therefore, NSP-Wisconsin consolidates these limited partnerships in its consolidated financial statements. NSP-Wisconsin’s risk of loss for these partnerships is limited to its capital contributions, adjusted for any distributions and its share of undistributed profits and losses; no significant additional financial support has been, or is required to be provided to the limited partnerships by NSP-Wisconsin.

Amounts reflected in NSP-Wisconsin’s consolidated balance sheets for low-income housing limited partnerships include the following:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Current assets	$	—	$	—
Property, plant and equipment, net	1		1
Other noncurrent assets	—		—
Total assets	$	1	$	1
Current liabilities	$	—	$	—
Mortgages and other long-term debt payable	1		1
Other noncurrent liabilities	—		—
Total liabilities	$	1	$	1

Other

Guarantees — NSP-Wisconsin provides a guarantee for payment of customer loans related to NSP-Wisconsin’s farm rewiring program. NSP-Wisconsin’s exposure under the guarantee is based upon the net liability under the agreement. The guarantee issued by NSP-Wisconsin limits the exposure of NSP-Wisconsin to a maximum amount stated in the guarantee. The guarantee contains no recourse provisions and requires no collateral.

Guarantee issued and outstanding for NSP-Wisconsin:

(Millions of Dollars)	Guarantor	Guarantee Amount		Current Exposure		Triggering Event
Guarantee of customer loans for the Farm Rewiring Program (a)	NSP-Wisconsin	$	1	$	—	(b)

(a)As of Dec. 31, 2020, no claims were outstanding against the guarantee.

(b)The debtor becomes the subject of bankruptcy or other insolvency proceedings.

11. Segment Information

NSP-Wisconsin evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment.

NSP-Wisconsin has the following reportable segments:

•Regulated Electric — The regulated electric utility segment generates electricity which is transmitted and distributed in Wisconsin and Michigan.

•Regulated Natural Gas — The regulated natural gas utility segment purchases, transports, stores and distributes natural gas in portions of Wisconsin and Michigan.

NSP-Wisconsin also presents All Other, which includes operating segments with revenues below the necessary quantitative thresholds. Those operating segments primarily include investments in rental housing projects that qualify for low-income housing tax credits.

Asset and capital expenditure information is not provided for NSP-Wisconsin’s reportable segments. As an integrated electric and natural gas utility, NSP-Wisconsin operates significant assets that are not dedicated to a specific business segment. Reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations, which may not necessarily reflect the assets required for the operation of the business segments on a stand-alone basis.

Certain costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators across each segment. In addition, a general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising.

39

NSP-Wisconsin’s segment information:

(Millions of Dollars)	2020		2019		2018
Regulated Electric
Operating revenues - external (a)	$	855	$	845	$	879
Intersegment revenue	1		—		—
Total revenues	$	856	$	845	$	879
Depreciation and amortization	108		109		98
Interest charges and financing costs	34		34		32
Income tax expense	12		13		28
Net income	98		68		85
Regulated Natural Gas
Total revenues	$	119	$	136	$	142
Depreciation and amortization	48		29		28
Interest charges and financing costs	4		4		3
Income tax (benefit) expense	(20)		2		5
Net income	7		10		13
All Other
Total revenues (a)	$	—	$	—	$	1
Income tax expense (benefit)	1		1		(1)
Net income	2		1		—
Consolidated Total
Total revenues (a)	$	975	$	981	$	1,022
Reconciling eliminations	(1)		—		—
Total operating revenues	$	974	$	981	$	1,022
Depreciation and amortization	156		138		126
Interest charges and financing costs	38		38		35
Income tax (benefit) expense	(7)		16		32
Net income	107		79		98

(a)    Operating revenues include $168 million, $177 million and $158 million of intercompany revenue for the years ended Dec. 31, 2020, 2019 and 2018, respectively. See Note 12 for further information.

12. Related Party Transactions

Xcel Energy Services Inc. provides management, administrative and other services for the subsidiaries of Xcel Energy Inc., including NSP-Wisconsin. The services are provided and billed to each subsidiary in accordance with service agreements executed by each subsidiary. NSP-Wisconsin uses services provided by Xcel Energy Services Inc. whenever possible. Costs are charged directly to the subsidiary and are allocated if they cannot be directly assigned.

Xcel Energy Inc., NSP-Minnesota, NSP-Wisconsin, PSCo and SPS have established a utility money pool arrangement.

The electric production and transmission costs of the entire NSP System are shared by NSP-Minnesota and NSP-Wisconsin. The Interchange Agreement provides for the sharing of all costs of generation and transmission facilities of the system, including capital costs.

Significant affiliate transactions among the companies and related parties including billings under the Interchange Agreement for the years ended Dec. 31:

(Millions of Dollars)	2020		2019		2018
Operating revenues:
Electric	$	168	$	177	$	158
Operating expenses:
Purchased power	379		394		411
Transmission expense	61		64		63
Natural gas purchased for resale	1		1		—
Other operating expenses — paid to Xcel Energy Services Inc.	92		87		87

Accounts receivable and payable with affiliates at Dec. 31 were:

	2020				2019
(Millions of Dollars)	Accounts Receivable		Accounts Payable		Accounts Receivable		Accounts Payable
NSP-Minnesota	$	—	$	6	$	—	$	8
PSCo	1		—		—		—
Other subsidiaries of Xcel Energy Inc.	9		9		—		11
	$	10	$	15	$	—	$	19

13. Summarized Quarterly Financial Data (Unaudited)

	Quarter Ended
(Millions of Dollars)	March 31, 2020		June 30, 2020		Sept. 30, 2020		Dec. 31, 2020
Operating revenues	$	257	$	218	$	251	$	248
Operating income	41		23		46		31
Net income	34		12		40		21

	Quarter Ended
(Millions of Dollars)	March 31, 2019		June 30, 2019		Sept. 30, 2019		Dec. 31, 2019
Operating revenues	$	276	$	229	$	244	$	232
Operating income	42		22		48		19
Net income	24		9		29		17

ITEM 9 — CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

None.

40

ITEM 9A — CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

NSP-Wisconsin maintains a set of disclosure controls and procedures designed to ensure that information required to be disclosed in reports that it files or submits under the Securities Exchange Act of 1934 is recorded, processed, summarized, and reported within the time periods specified in SEC rules and forms. In addition, the disclosure controls and procedures ensure that information required to be disclosed is accumulated and communicated to management, including the CEO and CFO, allowing timely decisions regarding required disclosure. As of Dec. 31, 2020, based on an evaluation carried out under the supervision and with the participation of NSP-Wisconsin’s management, including the CEO and CFO, of the effectiveness of its disclosure controls and procedures, the CEO and CFO have concluded that NSP-Wisconsin’s disclosure controls and procedures were effective.

Internal Control Over Financial Reporting

No changes in NSP-Wisconsin’s internal control over financial reporting occurred during the most recent fiscal quarter that materially affected, or are reasonably likely to materially affect, NSP-Wisconsin’s internal control over financial reporting. NSP-Wisconsin maintains internal control over financial reporting to provide reasonable assurance regarding the reliability of the financial reporting. NSP-Wisconsin has evaluated and documented its controls in process activities, general computer activities, and on an entity-wide level.

During the year and in preparation for issuing its report for the year ended Dec. 31, 2020 on internal controls under section 404 of the Sarbanes-Oxley Act of 2002, NSP-Wisconsin conducted testing and monitoring of its internal control over financial reporting. Based on the control evaluation, testing and remediation performed, NSP-Wisconsin did not identify any material control weaknesses, as defined under the standards and rules issued by the Public Company Accounting Oversight Board, as approved by the SEC and as indicated in NSP-Wisconsin’s Management Report on Internal Controls over Financial Reporting, which is contained in Item 8 herein.

This annual report does not include an attestation report of NSP-Wisconsin’s independent registered public accounting firm regarding internal control over financial reporting. Management’s report was not subject to attestation by NSP-Wisconsin’s independent registered public accounting firm pursuant to the rules of the SEC that permit NSP-Wisconsin to provide only management’s report in this annual report.

ITEM 9B — OTHER INFORMATION

None.

PART III

Items 10, 11, 12 and 13 of Part III of Form 10-K have been omitted from this report for NSP-Wisconsin in accordance with conditions set forth in general instructions I(1)(a) and (b) of Form 10-K for wholly-owned subsidiaries.

ITEM 10 — DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

ITEM 11 — EXECUTIVE COMPENSATION

ITEM 12 — SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS

ITEM 13 — CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

Information required under this Item is contained in Xcel Energy Inc.’s definitive Proxy Statement for its 2021 Annual Meeting of Shareholders, which is incorporated by reference.

ITEM 14 — PRINCIPAL ACCOUNTANT FEES AND SERVICES

The information required by Item 14 of Form 10-K is set forth under the heading “Independent Registered Public Accounting Firm - Audit and Non-Audit Fees” in Xcel Energy Inc.’s Proxy Statement for the 2021 Annual Meeting of Shareholders which is expected to be filed with the SEC on or about April 6, 2021. Such information set forth under such heading is incorporated herein by this reference hereto.

41

PART IV

ITEM 15 — EXHIBIT AND FINANCIAL STATEMENT SCHEDULES

1	Consolidated Financial Statements
	Management Report on Internal Controls Over Financial Reporting — For the year ended Dec. 31, 2020.
	Report of Independent Registered Public Accounting Firm — Financial Statements
	Consolidated Statements of Income — For each of the three years ended Dec. 31, 2020, 2019 and 2018.
	Consolidated Statements of Comprehensive Income — For each of the three years ended Dec. 31, 2020, 2019 and 2018.
	Consolidated Statements of Cash Flows — For each of the three years ended Dec. 31, 2020, 2019 and 2018.
	Consolidated Balance Sheets — As of Dec. 31, 2020 and 2019.
	Consolidated Statements of Common Stockholder’s Equity — For each of the three years ended Dec. 31, 2020, 2019 and 2018.
2	Schedule II — Valuation and Qualifying Accounts and Reserves for each of the years ended Dec. 31, 2020, 2019 and 2018.
3	Exhibits
*	Indicates incorporation by reference
+	Executive Compensation Arrangements and Benefit Plans Covering Executive Officers and Directors
Exhibit Number	Description	Report or Registration Statement	Exhibit Reference
3.01*	Amended and restated articles of incorporation of NSP-Wisconsin	NSP-Wisconsin Form S-4 dated Jan. 21, 2004	3.01
3.02*	By-Laws of NSP-Wisconsin as Amended and Restated on Jan. 25, 2019	NSP-Wisconsin Form 10-K for the year ended Dec. 31, 2018	3.02
4.01*	Supplemental and Restated Trust Indenture, dated March 1, 1991, between NSP-Wisconsin and First Wisconsin Trust Company, providing for the issuance of First Mortgage Bonds	Xcel Energy Inc. Form S-3 dated April 18, 2018	4(c)(3)
4.02*	Trust Indenture dated Sept. 1, 2000 between NSP-Wisconsin and Firstar Bank, NA as Trustee	NSP-Wisconsin Form 8-K dated Sept. 25, 2000	4.01
4.03*	Supplemental Trust Indenture dated as of Sept. 1, 2008 between NSP-Wisconsin and U.S. Bank National Association, as successor Trustee, creating $200 million principal amount of 6.375% First Mortgage Bonds, Series due Sept. 1, 2038	NSP-Wisconsin Form 8-K dated Sept. 3, 2008	4.01
4.04*	Supplemental Trust Indenture dated as of Oct. 1, 2012 between NSP-Wisconsin and U.S. Bank National Association, as successor Trustee, creating $100 million principal amount of 3.70% First Mortgage Bonds, Series due Oct. 1, 2042	NSP-Wisconsin Form 8-K dated Oct. 10, 2012	4.01
4.05*	Supplemental Trust Indenture dated as of June 1, 2014 between NSP-Wisconsin and U.S. Bank National Association, as successor Trustee, creating $100 million principal amount of 3.30% First Mortgage Bonds, Series due June 1, 2024	NSP-Wisconsin Form 8-K dated June 23, 2014	4.01
4.06*	Supplemental Trust Indenture dated as of Nov 1, 2017 between NSP-Wisconsin and U.S. Bank National Association, as successor Trustee, creating $100 million in aggregate principal amount of 3.75% First Mortgage Bonds, Series due Dec. 1, 2047	NSP-Wisconsin Form 8-K dated Dec. 4, 2017	4.01
4.07*	Supplemental Indenture dated as of Sept. 1, 2018 between NSP-Wisconsin and U.S. Bank National Association, as successor Trustee, creating 4.20% First Mortgage Bonds, Series due Sept. 1, 2048	NSP-Wisconsin Form 8-K dated Sept. 12, 2018	4.01
4.08*	Supplemental Indenture dated as of May 18, 2020 between NSP-Wisconsin and U.S. Bank National Association, as Trustee, creating $100 million principal amount of 3.05% First Mortgage Bonds, Series due 2051	NSP-Wisconsin Form 8-K dated May 26, 2020	4.01
10.01*+	Xcel Energy Inc. Nonqualified Pension Plan (2009 Restatement)	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2008	10.02
10.02*+	Xcel Energy Senior Executive Severance and Change-in-Control Policy (2009 Restatement)	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2008	10.05
10.03*+	Second Amendment to Exhibit 10.02 dated Oct. 26, 2011	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2011	10.18
10.04*+	Fifth Amendment to Exhibit 10.02 dated May 3, 2016	Xcel Energy Inc. Form 10-Q for the quarter ended June 30, 2016	10.01
10.05*+	Seventh Amendment to Exhibit 10.02 dated May 7, 2018	Xcel Energy Inc. Form 10-Q for the quarter ended June 30, 2018	10.01
10.06*+	Eighth Amendment to Exhibit 10.02 dated March 31, 2020	Xcel Energy Inc. Form 10-Q for the quarter ended March 31, 2020	10.02
10.07*+	Ninth Amendment to Exhibit 10.02 dated May 22, 2020	Xcel Energy Inc. Form 10-Q for the quarter ended June 30, 2020	10.01
10.08*+	Xcel Energy Inc. Supplemental Executive Retirement Plan as amended and restated Jan. 1, 2009	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2008	10.17
10.09*+	Xcel Energy Inc. Executive Annual Incentive Plan (as amended and restated effective Feb. 17, 2010)	Xcel Energy Inc. Definitive Proxy Statement dated April 6, 2010	Appendix A
10.10*+	First Amendment to Exhibit 10.09 dated Feb. 20, 2013	Xcel Energy Inc. Form 10-Q for the quarter ended March 31, 2013	10.01
10.11*+	Xcel Energy Inc. Executive Annual Incentive Award Plan Form of Restricted Stock Agreement	Xcel Energy Inc. Form 10-Q for the quarter ended Sept. 30, 2009	10.08
10.12*+	Xcel Energy Inc. Nonqualified Deferred Compensation Plan (2009 Restatement)	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2008	10.07
10.13*+	First Amendment to Exhibit 10.12 effective Nov. 29, 2011	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2011	10.17
10.14*+	Second Amendment to Exhibit 10.12 dated May 21, 2013	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2013	10.22

42

10.15*+	Third Amendment to Exhibit 10.12 dated Sept. 30, 2016	Xcel Energy inc. Form 10-Q for the quarter ended Sept. 30, 2016	10.01
10.16*+	Fourth Amendment to Exhibit 10.12 dated Oct. 23, 2017	Xcel Energy Inc. Form 10-Q for the quarter ended Sept. 30, 2017	10.01
10.17*+	Xcel Energy Inc. Amended and Restated 2015 Omnibus Incentive Plan	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2018	10.34
10.18*+	Form of Terms and Conditions under the Xcel Energy Inc. Amended and Restated 2015 Omnibus Incentive Plan for Awards of Restricted Stock Units and/or Performance Share Units	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2018	10.35
10.19*+	Form of Award Agreement for Restricted Stock Units and/or Performance Share Units under the Xcel Energy Inc. Amended and Restated 2015 Omnibus Incentive Plan Award Agreement for awards since 2020	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2019	10.32
10.20*+	Stock Equivalent Plan for Non-Employee Directors of Xcel Energy Inc. as amended and restated effective Feb. 23, 2011	Xcel Energy Inc. Definitive Proxy Statement dated April 5, 2011	Appendix A
10.21*+	Stock Equivalent Program for Non-Employee Directors of Xcel Energy Inc. under the Xcel Energy Inc. 2015 Omnibus Incentive Plan	Xcel Energy Inc. Form 8-K dated May 26, 2015	10.02
10.22*+	Summary of Non-Employee Director Compensation, effective as of Sept. 1, 2019	Xcel Energy Form 10-K for the year ended Dec. 31, 2020	10.22
10.23*+	Stock Program for Non-Employee Directors of Xcel Energy Inc. as Amended and Restated on Dec. 12, 2017 under the 2015 Omnibus Incentive Plan	Xcel Energy Inc. Form 10-K for the year ended Dec. 31, 2018	10.36
10.24*+	Form of Services Agreement between Xcel Energy Services Inc. and utility companies	Xcel Energy Inc. Form U5B dated Nov. 16, 2000	H-1
10.25*	Restated Interchange Agreement dated Jan. 16, 2001 between NSP-Wisconsin and NSP-Minnesota	NSP-Wisconsin Form S-4 dated Jan. 21, 2004	10.01
10.26*	Third Amended and Restated Credit Agreement, dated as of June 7, 2019 among NSP-Wisconsin, as Borrower, the several lenders from time to time parties thereto, JPMorgan Chase Bank, N.A., as Administrative Agent, Bank of America, N.A. and Barclays Bank Plc, as Syndication Agents, Wells Fargo Bank, National Association, MUFG Bank, Ltd., and Citibank, N.A., as Documentation Agents	Xcel Energy Inc. Form 8-K dated June 7, 2019	99.05
23.01	Consent of Independent Registered Public Accounting Firm.
31.01	Principal Executive Officer’s certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
31.02	Principal Financial Officer’s certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
32.01	Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS	Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH	Inline XBRL Schema
101.CAL	Inline XBRL Calculation
101.DEF	Inline XBRL Definition
101.LAB	Inline XBRL Label
101.PRE	Inline XBRL Presentation
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

SCHEDULE II

NSP-Wisconsin and Subsidiaries Valuation and Qualifying Accounts Years Ended Dec. 31

	Allowance for bad debts
(Millions of Dollars)	2020		2019		2018
Balance at Jan. 1	$	6	$	6	$	5
Additions charged to costs and expenses	7		7		4
Additions charged to other accounts (a)	1		2		1
Deductions from reserves (b)	(6)		(9)		(4)
Balance at Dec. 31	$	8	$	6	$	6

(a)Recovery of amounts previously written-off.

(b)Deductions related primarily to bad debt write-offs.

ITEM 16 — FORM 10-K SUMMARY

None.

43

Signatures

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this annual report to be signed on its behalf by the undersigned thereunto duly authorized.

	NORTHERN STATES POWER COMPANY (A WISCONSIN CORPORATION)
Feb. 17, 2021	/s/ BRIAN J. VAN ABEL
	Brian J. Van Abel
	Executive Vice President, Chief Financial Officer and Director

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities on the date indicated above.

/s/ BEN FOWKE	/s/ MARK E. STOERING
Ben Fowke	Mark E. Stoering
Chairman, Chief Executive Officer and Director	President and Director
(Principal Executive Officer)
/s/ BRIAN J. VAN ABEL	/s/ JEFFREY S. SAVAGE
Brian J. Van Abel	Jeffrey S. Savage
Executive Vice President, Chief Financial Officer and Director	Senior Vice President, Controller
(Principal Financial Officer)	(Principal Accounting Officer)
/s/ ROBERT C. FRENZEL
Robert C. Frenzel
Executive Vice President, Chief Operating Officer and Director

SUPPLEMENTAL INFORMATION TO BE FURNISHED WITH REPORTS FILED PURSUANT TO SECTION 15(D) OF THE ACT BY REGISTRANTS WHICH HAVE NOT REGISTERED SECURITIES PURSUANT TO SECTION 12 OF THE ACT

NSP-Wisconsin has not sent, and does not expect to send, an annual report or proxy statement to its security holder.

44

EX-23.01

Exhibit 23.01

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statement No. 333-224333-03 on Form S-3 of our report dated February 17, 2021, relating to the consolidated financial statements and financial statement schedule of Northern States Power Company, a Wisconsin corporation, and subsidiaries appearing in this Annual Report on Form 10-K of Northern States Power Company, a Wisconsin corporation, for the year ended December 31, 2020.

/s/ DELOITTE & TOUCHE LLP

Minneapolis, Minnesota

February 17, 2021

EX-31.01

Exhibit 31.01

CERTIFICATION

I, Ben Fowke, certify that:

1.I have reviewed this report on Form 10-K of Northern States Power Company (a Wisconsin corporation);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a.Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b.Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c.Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d.Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a.All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b.Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: Feb. 17, 2021

/s/ BEN FOWKE

Ben Fowke

Chairman, Chief Executive Officer and Director

1

EX-31.02

Exhibit 31.02

CERTIFICATION

I, Brian J. Van Abel, certify that:

1.I have reviewed this report on Form 10-K of Northern States Power Company (a Wisconsin corporation);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a.Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b.Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c.Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d.Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a.All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b.Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: Feb. 17, 2021

/s/ BRIAN J. VAN ABEL

Brian J. Van Abel

Executive Vice President, Chief Financial Officer and Director

2

EX-32.01

Exhibit 32.01

OFFICER CERTIFICATION

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report of Northern States Power Company, a Wisconsin corporation (NSP-Wisconsin), on Form 10-K for the year ended Dec. 31, 2020, as filed with the SEC on the date hereof (Form 10-K), each of the undersigned officers of NSP-Wisconsin certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to such officer’s knowledge:

(1)The Form 10-K fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)The information contained in the Form 10-K fairly presents, in all material respects, the financial condition and results of operations of NSP-Wisconsin as of the dates and for the periods expressed in the Form 10-K.

Date: Feb. 17, 2021

/s/ BEN FOWKE

Ben Fowke

Chairman, Chief Executive Officer and Director

/s/ BRIAN J. VAN ABEL

Brian J. Van Abel

Executive Vice President, Chief Financial Officer and Director

The foregoing certification is being furnished solely pursuant to 18 U.S.C. Section 1350 and is not being filed as part of the Report or as a separate disclosure document.

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to NSP-Wisconsin and will be retained by NSP-Wisconsin and furnished to the SEC or its staff upon request.

1

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Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 17, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-03140
Entity Incorporation, State or Country Code	WI
Entity Tax Identification Number	39-0508315
Entity Address, Address Line One	1414 West Hamilton Avenue
Entity Address, City or Town	Eau Claire
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	54701
City Area Code	715
Local Phone Number	839-2625
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		933,000
Entity Registrant Name	NORTHERN STATES POWER CO
Entity Central Index Key	0000072909
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Public Float			$ 0

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Accounting Pronouncements

12 Months Ended

Dec. 31, 2020

Accounting Standards Update and Change in Accounting Principle [Abstract]

Accounting Pronouncements

Recently Adopted

Credit Losses — In 2016, the FASB issued Financial Instruments - Credit Losses, Topic 326 (ASC Topic 326), which changes how entities account for losses on receivables and certain other assets. The guidance requires use of a current expected credit loss model, which may result in earlier recognition of credit losses than under previous accounting standards.

NSP-Wisconsin implemented the guidance using a modified-retrospective approach, recognizing an immaterial cumulative effect charge (after tax) to retained earnings on Jan 1. 2020. The Jan. 1, 2020 adoption of ASC Topic 326 did not have a significant impact on NSP-Wisconsin’s consolidated financial statements.

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CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating revenues
Electric, non-affiliates	$ 687	$ 668	$ 721
Regulated Operating Revenue, Electric, Affiliate	168	177	158
Natural gas	119	136	142
Other	0	0	1
Total operating revenues	974	981	1,022
Operating expenses
Electric fuel and purchased power, non-affiliates	13	11	13
Purchased power, affiliates	379	394	411
Cost of natural gas sold and transported	53	65	69
Operating and maintenance expenses	191	201	203
Conservation program expenses	13	12	12
Depreciation and amortization	156	138	126
Taxes (other than income taxes)	28	29	29
Total operating expenses	833	850	863
Operating income	141	131	159
Other Income and Expenses [Abstract]
Other expense, net	(8)	(1)	(3)
Allowance for funds used during construction — equity	5	3	9
Interest charges and financing costs
Interest charges — includes other financing costs of $1, $1 and $2, respectively	40	39	39
Allowance for funds used during construction — debt	(2)	(1)	(4)
Total interest charges and financing costs	38	38	35
Income before income taxes	100	95	130
Income tax (benefit) expense	(7)	16	32
Net income	$ 107	$ 79	$ 98

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CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest charges and financing costs
Other financing costs	$ 1	$ 1	$ 2

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CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income	$ 107	$ 79	$ 98
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	158	139	128
Deferred income taxes	(36)	5	23
Allowance for equity funds used during construction	(5)	(3)	(9)
Provision for bad debts	7	7	4
Changes in operating assets and liabilities:
Accounts receivable	(12)	(10)	(5)
Accrued unbilled revenues	0	3	4
Inventories	(5)	(8)	(8)
Other current assets	(3)	13	2
Accounts payable	(3)	(10)	(9)
Net regulatory assets and liabilities	0	15	(20)
Other current liabilities	4	11	(13)
Pension and other employee benefit obligations	(7)	(7)	(15)
Other, net	(3)	0	3
Net cash provided by operating activities	202	234	183
Investing activities
Capital/construction expenditures	(238)	(212)	(226)
Net cash used in investing activities	(238)	(212)	(226)
Financing activities
(Repayments of) proceeds from short-term borrowings, net	(46)	13	40
Proceeds from issuance of long-term debt	97	0	197
Repayments of long-term debt	0	0	(151)
Capital contributions from parent	56	48	49
Dividends paid to parent	(70)	(84)	(91)
Net cash provided by (used in) financing activities	37	(23)	44
Net change in cash, cash equivalents and restricted cash	1	(1)	1
Cash, cash equivalents and restricted cash at beginning of period	1	2	1
Cash, cash equivalents and restricted cash at end of period	2	1	2
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(36)	(36)	(33)
Cash paid for income taxes, net	(26)	0	(21)
Other Noncash Investing and Financing Items [Abstract]
Supplemental disclosure of non-cash investing and financing transactions:	21	29	32
Inventory transfers to plant, property and equipment	5	9	8
Allowance for Funds Used During Construction, Investing Activities	$ 5	$ 3	$ 9

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CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 2
Accounts receivable, net	70	$ 59
Accrued unbilled revenues	53	53
Other receivables	1	0
Inventories	15	16
Regulatory assets	19	72
Prepaid taxes	24	23
Prepayments and other	7	5
Total current assets	191	229
Property, Plant and Equipment, Net	2,484	2,359
Other assets
Regulatory assets	215	224
Other investments	3	3
Other	1	1
Total other assets	219	228
Total assets	2,894	2,816
Current liabilities
Current portion of long-term debt	19	0
Short-term debt	19	65
Accounts payable	41	54
Accounts payable to affiliates	15	19
Dividends payable to parent	19	15
Regulatory liabilities	31	79
Taxes accrued	12	7
Environmental liabilities	4	6
Accrued interest	10	9
Other	15	20
Total current liabilities	185	274
Deferred credits and other liabilities
Deferred income taxes	307	298
Deferred investment tax credits	6	7
Regulatory liabilities	350	371
Environmental liabilities	16	18
Customer advances	20	19
Pension and employee benefit obligations	28	33
Other	27	21
Total deferred credits and other liabilities	754	767
Commitments and contingencies
Capitalization
Long-term debt	887	808
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at Dec. 31, 2020 and Dec. 31, 2019, respectively	93	93
Additional paid in capital	605	537
Retained earnings	370	337
Total common stockholder's equity	1,068	967
Total liabilities and equity	$ 2,894	$ 2,816

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CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares outstanding (in shares)	933,000	933,000

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CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings
Beginning Balance at Dec. 31, 2017	$ 876	$ 93	$ 449	$ 334
Balance (in shares) at Dec. 31, 2017		933,000
Increase (Decrease) in Stockholder's Equity
Net income	98			98
Dividends, Common Stock, Cash	(93)			(93)
Contribution of capital by parent	61		61
Ending Balance at Dec. 31, 2018	942	$ 93	510	339
Balance (in shares) at Dec. 31, 2018		933,000
Increase (Decrease) in Stockholder's Equity
Net income	79			79
Dividends, Common Stock, Cash	(81)			(81)
Contribution of capital by parent	27		27
Ending Balance at Dec. 31, 2019	$ 967	$ 93	537	337
Balance (in shares) at Dec. 31, 2019	933,000	933,000
Increase (Decrease) in Stockholder's Equity
Net income	$ 107			107
Dividends, Common Stock, Cash	(74)			(74)
Contribution of capital by parent	68		68
Ending Balance at Dec. 31, 2020	$ 1,068	$ 93	$ 605	$ 370
Balance (in shares) at Dec. 31, 2020	933,000	933,000

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Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

General — NSP-Wisconsin is engaged in the regulated generation, transmission, distribution and sale of electricity and in the regulated purchase, transportation, distribution and sale of natural gas.

NSP-Wisconsin’s consolidated financial statements include its wholly-owned subsidiaries and VIEs for which it is the primary beneficiary. In the consolidation process, all intercompany transactions and balances are eliminated. NSP-Wisconsin has investments in certain transmission facilities jointly owned with nonaffiliated utilities.

NSP-Wisconsin’s proportionate share of jointly owned facilities is recorded as property, plant and equipment on the consolidated balance sheets and NSP-Wisconsin’s proportionate share of the operating costs associated with these facilities is included in its consolidated statements of income.

NSP-Wisconsin’s consolidated financial statements are presented in accordance with GAAP. All of NSP-Wisconsin’s underlying accounting records also conform to the FERC uniform system of accounts or to systems required by various state regulatory commissions. Certain amounts in the consolidated financial statements or notes have been reclassified for comparative purposes; however, such reclassifications did not affect net income, total assets, liabilities, equity or cash flows.

NSP-Wisconsin has evaluated events occurring after Dec. 31, 2020 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation.

Use of Estimates — NSP-Wisconsin uses estimates based on the best information available in recording transactions and balances resulting from business operations. Estimates are used on items such as plant depreciable lives or potential disallowances, AROs, certain regulatory assets and liabilities, tax provisions, uncollectible amounts, environmental costs, unbilled revenues, jurisdictional fuel and energy cost allocations and actuarially determined benefit costs. Recorded estimates are revised when better information becomes available or actual amounts can be determined. Revisions can affect operating results.

Regulatory Accounting — NSP-Wisconsin accounts for income and expense items in accordance with accounting guidance for regulated operations. Under this guidance:

•Certain costs, which would otherwise be charged to expense or other comprehensive income, are deferred as regulatory assets based on the expected ability to recover the costs in future rates.

•Certain credits, which would otherwise be reflected as income or other comprehensive income, are deferred as regulatory liabilities based on the expectation the amounts will be returned to customers in future rates or because the amounts were collected in rates prior to the costs being incurred.

Estimates of recovering deferred costs and returning deferred credits are based on specific ratemaking decisions or precedent for each item. Regulatory assets and liabilities are amortized consistent with the treatment in the rate setting process.

If changes in the regulatory environment occur, NSP-Wisconsin may no longer be eligible to apply this accounting treatment and may be required to eliminate regulatory assets and liabilities from its balance sheets. Such changes could have a material effect on NSP-Wisconsin’s results of operations, financial condition and cash flows.

See Note 4 for further information.

Income Taxes — NSP-Wisconsin accounts for income taxes using the asset and liability method, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. NSP-Wisconsin defers income taxes for all temporary differences between pretax financial and taxable income and between the book and tax bases of assets and liabilities. NSP-Wisconsin uses rates that are scheduled to be in effect when the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the period that includes the enactment date.

The effects of NSP-Wisconsin’s tax rate changes are generally subject to a normalization method of accounting. Therefore, the revaluation of most of its net deferred taxes upon a tax rate reduction results in the establishment of a net regulatory liability, which would be refundable to utility customers over the remaining life of the related assets. NSP-Wisconsin anticipates that a tax rate increase would result in the establishment of a regulatory asset, subject to regulatory approval.

Reversal of certain temporary differences are accounted for as current income tax expense due to the effects of past regulatory practices when deferred taxes were not required to be recorded due to the use of flow through accounting for ratemaking purposes. Tax credits are recorded when earned unless there is a requirement to defer the benefit and amortize it over the book depreciable lives of the related property. The requirement to defer and amortize tax credits only applies to federal ITCs related to public utility property. Utility rate regulation also has resulted in the recognition of regulatory assets and liabilities related to income taxes. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized.

NSP-Wisconsin follows the applicable accounting guidance to measure and disclose uncertain tax positions that it has taken or expects to take in its income tax returns. NSP-Wisconsin recognizes a tax position in its consolidated financial statements when it is more likely than not that the position will be sustained upon examination based on the technical merits of the position. Recognition of changes in uncertain tax positions are reflected as a component of income tax expense.

NSP-Wisconsin reports interest and penalties related to income taxes within other (expense) income or interest charges in the consolidated statements of income.

Xcel Energy Inc. and its subsidiaries, including NSP-Wisconsin, file consolidated federal income tax returns as well as consolidated or separate state income tax returns. Federal income taxes paid by Xcel Energy Inc. are allocated to its subsidiaries based on separate company computations. A similar allocation is made for state income taxes paid by Xcel Energy Inc. in connection with consolidated state filings. Xcel Energy Inc. also allocates its own income tax benefits to its direct subsidiaries.

See Note 7 for further information.

Property, Plant and Equipment and Depreciation in Regulated Operations — Property, plant and equipment is stated at original cost. The cost of plant includes direct labor and materials, contracted work, overhead costs and AFUDC. The cost of plant retired is charged to accumulated depreciation and amortization. Amounts recovered in rates for future removal costs are recorded as regulatory liabilities. Significant additions or improvements extending asset lives are capitalized, while repairs and maintenance costs are charged to expense as incurred. Maintenance and replacement of items determined to be less than a unit of property are charged to operating expenses as incurred. Planned maintenance activities are charged to operating expense unless the cost represents the acquisition of an additional unit of property or the replacement of an existing unit of property.

Property, plant and equipment is tested for impairment when it is determined that the carrying value of the assets may not be recoverable. A loss is recognized in the current period if it becomes probable that part of a cost of a plant under construction or recently completed plant will be disallowed for recovery from customers and a reasonable estimate of the disallowance can be made. For investments in property, plant and equipment that are abandoned and not expected to go into service, incurred costs and related deferred tax amounts are compared to the discounted estimated future rate recovery, and a loss is recognized, if necessary.

NSP-Wisconsin records depreciation expense using the straight-line method over the plant’s useful life. Actuarial life studies are performed and submitted to the state and federal commissions for review. Upon acceptance by the various commissions, the resulting lives and net salvage rates are used to calculate depreciation. Plant removal costs are recovered in rates as authorized by the appropriate regulatory entities. The amount of removal costs are based on current factors used in existing depreciation rates. Depreciation expense, expressed as a percentage of average depreciable property, was approximately 3.6% in 2020, 3.6% in 2019 and 3.5% in 2018.

See Note 3 for further information.

AROs — NSP-Wisconsin accounts for AROs under accounting guidance that requires a liability for the fair value of an ARO to be recognized in the period in which it is incurred if it can be reasonably estimated, with the offsetting associated asset retirement costs capitalized as a long-lived asset. The liability is generally increased over time by applying the effective interest method of accretion, and the capitalized costs are depreciated over the useful life of the long-lived asset. Changes resulting from revisions to the timing or amount of expected asset retirement cash flows are recognized as an increase or a decrease in the ARO.

See Note 10 for further information.

Benefit Plans and Other Postretirement Benefits — NSP-Wisconsin maintains pension and postretirement benefit plans for eligible employees. Recognizing the cost of providing benefits and measuring the projected benefit obligation of these plans requires management to make various assumptions and estimates.

Certain unrecognized actuarial gains and losses and unrecognized prior service costs or credits are deferred as regulatory assets and liabilities, rather than recorded as other comprehensive income, based on regulatory recovery mechanisms.

See Note 9 for further information.

Environmental Costs — Environmental costs are recorded when it is probable NSP-Wisconsin is liable for remediation costs and the liability can be reasonably estimated. Costs are deferred as a regulatory asset if it is probable that the costs will be recovered from customers in future rates. Otherwise, the costs are expensed. If an environmental expense is related to facilities currently in use, such as emission-control equipment, the cost is capitalized and depreciated over the life of the plant.

Estimated remediation costs are regularly adjusted as estimates are revised and remediation proceeds. If other participating potentially responsible parties exist and acknowledge their potential involvement with a site, costs are estimated and recorded only for NSP-Wisconsin’s expected share of the cost.

Future costs of restoring sites are treated as a capitalized cost of plant retirement. The depreciation expense levels recoverable in rates include a provision for removal expenses. Removal costs recovered in rates before the related costs are incurred are classified as a regulatory liability.

See Note 10 for further information.

Revenue from Contracts with Customers — Performance obligations related to the sale of energy are satisfied as energy is delivered to customers. NSP-Wisconsin recognizes revenue that corresponds to the price of the energy delivered to the customer. The measurement of energy sales to customers is generally based on the reading of their meters, which occurs systematically throughout the month. At the end of each month, amounts of energy delivered to customers since the date of the last meter reading are estimated, and the corresponding unbilled revenue is recognized.

NSP-Wisconsin does not recognize a separate financing component of its collections from customers as contract terms are short-term in nature. NSP-Wisconsin presents its revenues net of any excise or sales taxes or fees.

NSP-Wisconsin has various rate-adjustment mechanisms that provide for the recovery of natural gas, electric fuel and purchased energy costs. Cost-adjustment tariffs may increase or decrease the level of revenue collected from customers and are revised periodically for differences between the total amount collected under the clauses and the costs incurred. When applicable, fuel cost over-recoveries (the excess of fuel revenue billed to customers over fuel costs incurred) are deferred as regulatory liabilities and under-recoveries (the excess of fuel costs incurred over fuel revenues billed to customers) are deferred as regulatory assets. NSP-Wisconsin must submit a forward looking fuel cost plan annually for approval by the PSCW. The rules also allow for deferral of any under-recovery or over-recovery of fuel costs in excess of a 2% annual tolerance band, for future rate recovery or refund, subject to PSCW approval.

Cash and Cash Equivalents — NSP-Wisconsin considers investments in instruments with a remaining maturity of three months or less at the time of purchase to be cash equivalents.

Accounts Receivable and Allowance for Bad Debts — Accounts receivable are stated at the actual billed amount net of an allowance for bad debts. NSP-Wisconsin establishes an allowance for uncollectible receivables based on a policy that reflects its expected exposure to the credit risk of customers.

As of Dec. 31, 2020 and 2019, the allowance for bad debts was $8 million and $6 million, respectively.

Inventory — Inventory is recorded at average cost and consisted of the following:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Inventories
Materials and supplies	$	7	$	7
Fuel	4		4
Natural gas	4		5
Total inventories	$	15	$	16

Fair Value Measurements — NSP-Wisconsin presents cash equivalents, interest rate derivatives and commodity derivatives at estimated fair values in its consolidated financial statements. Cash equivalents are recorded at cost plus accrued interest; money market funds are measured using quoted NAVs. For interest rate derivatives, quoted prices based primarily on observable market interest rate curves are used to establish fair value. For commodity derivatives, the most observable inputs available are generally used to determine the fair value of each contract. In the absence of a quoted price, NSP-Wisconsin may use quoted prices for similar contracts or internally prepared valuation models to determine fair value.

For the pension and postretirement plan assets published trading data and pricing models, generally using the most observable inputs available, are utilized to estimate fair value for each security.

See Notes 8 and 9 for further information.

Derivative Instruments — NSP-Wisconsin uses derivative instruments in connection with its utility commodity price and interest rate activities, including forward contracts, futures, swaps and options. Any derivative instruments not qualifying for the normal purchases and normal sales exception are recorded on the consolidated balance sheets at fair value as derivative instruments. Classification of changes in fair value for those derivative instruments is dependent on the designation of a qualifying hedging relationship. Changes in fair value of derivative instruments not designated in a qualifying hedging relationship are reflected in current earnings or as a regulatory asset or liability. Classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

Interest rate hedging transactions are recorded as a component of interest expense. NSP-Wisconsin is allowed to recover in electric or natural gas rates the costs of certain financial instruments purchased to reduce commodity cost volatility.

Normal Purchases and Normal Sales — NSP-Wisconsin enters into contracts for purchases and sales of commodities for use in its operations. At inception, contracts are evaluated to determine whether a derivative exists and/or whether an instrument may be exempted from derivative accounting if designated as a normal purchase or normal sale.

See Note 8 for further information.

Other Utility Items

AFUDC — AFUDC represents the cost of capital used to finance utility construction activity. AFUDC is computed by applying a composite financing rate to qualified CWIP. The amount of AFUDC capitalized as a utility construction cost is credited to other nonoperating income (for equity capital) and interest charges (for debt capital). AFUDC amounts capitalized are included in NSP-Wisconsin’s rate base for establishing utility rates.

Alternative Revenue — Certain rate rider mechanisms qualify as alternative revenue programs. These mechanisms arise from costs imposed upon the utility by action of a regulator or legislative body related to an environmental, public safety or other mandate. When certain criteria are met, including expected collection within 24 months, revenue is recognized equal to the revenue requirement, which may include return on rate base items and incentives. The mechanisms are revised periodically for differences between total amount collected and the revenue recognized, which may increase or decrease the level of revenue collected from customers. Alternative revenues arising from these programs are presented on a gross basis and disclosed separately from revenue from contracts with customers.

See Note 6 for further information.

Conservation Programs — NSP-Wisconsin participates in and funds conservation programs in its retail jurisdictions to assist customers in conserving energy and reducing peak demand on the electric and natural gas systems. NSP-Wisconsin recovers approved conservation program costs in base rate revenue.

For operations in the state of Wisconsin, NSP-Wisconsin is required to contribute 1.2% of its three-year average annual operating revenues to the statewide energy efficiency and renewable resource program Focus on Energy. Funding is collected through base rates, and there is no financial incentive provided to the utility. The PSCW has full oversight of Focus on Energy including auditing and verification of programs. The program portfolio is outsourced to a third-party administrator who subcontracts as necessary to implement programs.

Emission Allowances — Emission allowances are recorded at cost, including broker commission fees. The inventory accounting model is utilized for all emission allowances and sales of these allowances are included in electric revenues.

RECs — Cost of RECs that are utilized for compliance is recorded as electric fuel and purchased power expense.

Sales of RECs are recorded in electric revenues on a gross basis. Cost of these RECs are recorded in electric fuel and purchased power expense.

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Property Plant and Equipment Property Plant and Equipment

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment Disclosure

Major classes of property, plant and equipment

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Property, plant and equipment, net
Electric plant	$	3,197	$	3,025
Natural gas plant	391		365
Common and other property	221		201
CWIP	71		83
Total property, plant and equipment	3,880		3,674
Less accumulated depreciation	(1,396)		(1,315)
Property, plant and equipment, net	$	2,484	$	2,359

Joint Ownership of Transmission Facilities

Jointly owned assets as of Dec. 31, 2020:

(Millions of Dollars, Except Percent Owned)	Plant in Service		Accumulated Depreciation		CWIP		Percent Owned
Electric transmission:
La Crosse, WI to Madison, WI	$	188	$	12	$	—	37	%
CapX2020	169		23		—		80
Total	$	357	$	35	$	—

NSP-Wisconsin’s share of operating expenses and construction expenditures is included in the applicable utility accounts. Respective owners are responsible for providing their own financing.

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Regulatory Assets and Liabilities

12 Months Ended

Dec. 31, 2020

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Assets and Liabilities

Regulatory assets and liabilities are created for amounts that regulators may allow to be collected or may require to be paid back to customers in future electric and natural gas rates. NSP-Wisconsin would be required to recognize the write-off of regulatory assets and liabilities in net income or other comprehensive income if changes in the utility industry no longer allow for the application of regulatory accounting guidance under GAAP.

Components of regulatory assets:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2020				Dec. 31, 2019
Regulatory Assets			Current		Noncurrent		Current		Noncurrent
Environmental remediation costs	1, 10	Various	$	13	$	94	$	35	$	108
Pension and retiree medical obligations	9	Various	4		67		12		70
State commission adjustments		Plant lives	1		20		1		19
Recoverable deferred taxes on AFUDC		Plant lives	—		18		—		17
Losses on reacquired debt		Term of related debt	—		2		—		2
Excess deferred taxes — TCJA	7	Various	—		—		23		—
Other		Various	1		14		1		8
Total regulatory assets			$	19	$	215	$	72	$	224

Components of regulatory liabilities:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2020				Dec. 31, 2019
Regulatory Liabilities			Current		Noncurrent		Current		Noncurrent
Plant removal costs	1, 10	Various	$	—	$	184	$	—	$	171
Deferred income tax adjustments and TCJA refunds (a)	7	Various	—		161		51		196
Deferred electric production and natural gas costs		Less than one year	17		1		17		—
United States Department of Energy Settlement		Less than one year	12		—		10		—
Other		Various	2		4		1		4
Total regulatory liabilities			$	31	$	350	$	79	$	371

(a)    Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA.

At Dec. 31, 2020 and 2019, NSP-Wisconsin’s regulatory assets not earning a return primarily included the unfunded portion of pension and retiree medical obligations. In addition, at Dec. 31, 2020 and 2019, regulatory assets included $0 million and $7 million, respectively, of past expenditures not earning a return. Amount is related to funded pension obligations.

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Debt

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Borrowings and Other Financing Instruments

5. Borrowings and Other Financing Instruments

Short Term Borrowings

Short-Term Debt — NSP-Wisconsin meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility.

Commercial paper outstanding for NSP-Wisconsin was as follows:

(Millions of Dollars, Except Interest Rates)	Three Months Ended Dec. 31, 2020			Year Ended
				2020			2019			2018
Borrowing limit	$	150		$	150		$	150		$	150
Amount outstanding at period end	19			19			65			51
Average amount outstanding	4			30			51			28
Maximum amount outstanding	24			95			93			103
Weighted average interest rate, computed on a daily basis	0.17		%	1.59		%	2.38		%	2.31		%
Weighted average interest rate at period end	0.17			0.17			1.97			2.89

Letters of Credit — NSP-Wisconsin may use letters of credit, typically with terms of one year, to provide financial guarantees for certain operating obligations. At Dec. 31, 2020 and 2019, there were no letters of credit outstanding.

Credit Facility — In order to use commercial paper programs to fulfill short-term funding needs, NSP-Wisconsin must have revolving credit facilities in place at least equal to the amount of their respective commercial paper borrowing limits and cannot issue commercial paper in an aggregate amount exceeding available capacity under these credit facilities. The lines of credit provide short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

Amended Credit Agreement — In June 2019, NSP-Wisconsin entered into an amended five-year credit agreement with a syndicate of banks. The amended credit agreements has substantially the same terms and conditions as the prior credit agreement with the exception of the maturity, which is June 2024.

Features of the credit facility:

Debt-to-Total Capitalization Ratio (a)				Amount Facility May Be Increased (millions)	Additional Periods for Which a One-Year Extension May Be Requested (b)
2020		2019
46	%	48	%	N/A	1

(a)    The credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%.

(b)    All extension requests are subject to majority bank group approval.

The credit facility has a cross-default provision that NSP-Wisconsin would be in default on borrowings under the facility if NSP-Wisconsin or any of its subsidiaries, whose total assets exceed 15% of NSP-Wisconsin’s consolidated total assets, default on certain indebtedness in an aggregate principal amount exceeding $75 million.

If NSP-Wisconsin does not comply with the covenant, an event of default may be declared, and if not remedied, any outstanding amounts due under the facility can be declared due by the lender. As of Dec. 31, 2020, NSP-Wisconsin was in compliance with all financial covenants.

NSP-Wisconsin had the following committed credit facility available as of Dec. 31, 2020 (in millions):

Credit Facility (a)		Drawn (b)		Available
$	150	$	19	$	131

(a)This credit facility matures in June 2024.

(b)Includes outstanding commercial paper.

All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. NSP-Wisconsin had no direct advances on the facility outstanding at Dec. 31, 2020 and 2019, respectively.

Other Short-Term Borrowings — Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, had an immaterial note payable to Xcel Energy Inc. at Dec. 31, 2020 and 2019, respectively.

Long-Term Borrowings and Other Financing Instruments

Generally, all property of NSP-Wisconsin is subject to the lien of its first mortgage indenture. Debt premiums, discounts and expenses are amortized over the life of the related debt. The premiums, discounts and expenses for refinanced debt are deferred and amortized over the life of new issuance.

Long-term debt obligations for NSP-Wisconsin as of Dec. 31 (millions of dollars):

Financing Instrument	Interest Rate		Maturity Date	2020		2019
City of La Crosse resource recovery bond	6.00	%	Nov 1, 2021	$	19	$	19
First mortgage bonds	3.30		June 15, 2024	100		100
First mortgage bonds	3.30		June 15, 2024	100		100
First mortgage bonds	6.38		Sept. 1, 2038	200		200
First mortgage bonds	3.70		Oct. 1, 2042	100		100
First mortgage bonds	3.75		Dec. 1, 2047	100		100
First mortgage bonds	4.20		Sept. 1, 2048	200		200
First mortgage bonds (a)	3.05		May 1, 2051	100		—
Unamortized discount				(4)		(3)
Unamortized debt issuance cost				(9)		(8)
Current maturities				(19)		—
Total long-term debt				$	887	$	808

(a)2020 financing.

Maturities of long-term debt:

(Millions of Dollars)
2021	$	19
2022	—
2023	—
2024	200
2025	—

Deferred Financing Costs — Deferred financing costs of approximately $9 million and $8 million, net of amortization, are presented as a deduction from the carrying amount of long-term debt at Dec. 31, 2020 and 2019, respectively. NSP-Wisconsin is amortizing these financing costs over the remaining maturity periods of the related debt.

Dividend Restrictions — NSP-Wisconsin’s dividends are subject to the FERC’s jurisdiction, which prohibits the payment of dividends out of capital accounts. Dividends are solely to be paid from retained earnings.

NSP-Wisconsin’s state regulatory commission additionally imposes dividend limitations, which are more restrictive than those imposed by the FERC.

Requirements and actuals as of Dec. 31, 2020:

Equity to Total Capitalization Ratio Required Range			Equity to Total Capitalization Ratio Actual
Low		High	2020
52.5	%	N/A	52.8	%

Unrestricted Retained Earnings			Total Capitalization		Limit on Total Capitalization (a)
$	7	million	1,940	million	N/A

(a) NSP-Wisconsin cannot pay annual dividends in excess of forecasted levels if its average equity-to-total capitalization ratio falls below the commission authorized level.

^[1],[2]

[1] All extension requests are subject to majority bank group approval.

[2] The credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%.

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Revenues

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Wisconsin’s operating revenues consisted of the following:

	Year Ended Dec. 31, 2020
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	258	$	64	$	322
C&I	411		49		460
Other	6		—		6
Total retail	675		113		788
Interchange	168		—		168
Other	—		4		4
Total revenue from contracts with customers	843		117		960
Alternative revenue and other	12		2		14
Total revenues	$	855	$	119	$	974

	Year Ended Dec. 31, 2019
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	240	$	73	$	313
C&I	409		57		466
Other	6		—		6
Total retail	655		130		785
Interchange	177		—		177
Other	1		4		5
Total revenue from contracts with customers	833		134		967
Alternative revenue and other	12		2		14
Total revenues	$	845	$	136	$	981

	Year Ended Dec. 31, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	255	$	73	$	—	$	328
C&I	444		62		—		506
Other	6		—		1		7
Total retail	705		135		1		841
Interchange	158		—		—		158
Other	4		5		—		9
Total revenue from contracts with customers	867		140		1		1,008
Alternative revenue and other	12		2		—		14
Total revenues	$	879	$	142	$	1	$	1,022

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Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

Federal Tax Loss Carryback Claims — In 2020, Xcel Energy identified certain expenses related to tax years 2009 - 2011 that qualify for an extended carryback claim. NSP-Wisconsin is not expected to accrue any income tax expense related to this adjustment.

Federal Audit — NSP-Wisconsin is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. Statute of limitations applicable to Xcel Energy’s consolidated federal income tax returns expire as follows:

Tax Year(s)	Expiration
2014 - 2016	July 2021

Additionally, the statute of limitations related to the federal tax loss carryback claim referenced above has been extended. Xcel Energy has recognized its best estimate of income tax expense that will result from a final resolution of this issue; however, the outcome and timing of a resolution is unknown.

In 2017, the IRS concluded the audit of tax years 2012 and 2013 and proposed an adjustment that would impact Xcel Energy’s NOL and ETR. Xcel Energy file a protest with the IRS. In April 2020, Xcel Energy and Appeals reached an agreement and no material adjustments were required.

In 2018, the IRS began an audit of tax years 2014 - 2016. In July 2020, Xcel Energy and the IRS reached an agreement and the related benefit was recognized.

State Audits — NSP-Wisconsin is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of Dec. 31, 2020, NSP-Wisconsin’s earliest open tax year that is subject to examination by state taxing authorities under applicable statutes of limitations is 2014. In 2018, Wisconsin began an audit of tax years 2014 - 2016. As of Dec. 31, 2020 no material adjustments have been proposed.

Unrecognized Tax Benefits — Unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which the ultimate deductibility is highly certain, but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the ETR, but would accelerate the payment to the taxing authority to an earlier period.

Unrecognized tax benefits — permanent vs. temporary:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Unrecognized tax benefit — Permanent tax positions	$	1	$	2
Unrecognized tax benefit — Temporary tax positions	1		1
Total unrecognized tax benefit	$	2	$	3

Changes in unrecognized tax benefits:

(Millions of Dollars)	2020		2019		2018
Balance at Jan. 1	$	3	$	3	$	2
Additions for tax positions of prior years	1		—		1
Reductions for tax positions of prior years	(2)		—		—
Balance at Dec. 31	$	2	$	3	$	3

Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
NOL and tax credit carryforwards	$	(2)	$	(2)

Net deferred tax liability associated with the unrecognized tax benefit amounts and related NOLs and tax credits carryforwards were $1 million for both Dec. 31, 2020 and Dec. 31, 2019.

As the IRS audits resume and state audits progress, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $1 million in the next 12 months.

Payable for interest related to unrecognized tax benefits is partially offset by the interest benefit associated with NOL and tax credit carryforwards. Payables for interest related to unrecognized tax benefits at Dec. 31, 2020, 2019 and 2018 were not material. No amounts were accrued for penalties related to unrecognized tax benefits as of Dec. 31, 2020, 2019 or 2018.

Other Income Tax Matters — NOL amounts represent the tax loss that is carried forward and tax credits represent the deferred tax asset. NOL and tax credit carryforwards as of Dec. 31 were as follows:

(Millions of Dollars)	2020		2019
Federal tax credit carryforwards	$	7	$	5
State NOL carryforward	2		2

Federal carryforward periods expire between 2031 and 2040 and state carryforward periods expire between 2031 and 2035.

Total income tax expense from operations differs from the amount computed by applying the statutory federal income tax rate to income before income tax expense.

Effective income tax rate for years ended Dec. 31:

	2020		2019 (a)		2018 (a)
Federal statutory rate	21.0	%	21.0	%	21.0	%
State income tax on pretax income, net of federal tax effect	6.2		6.2		6.2
Increases (decreases) in tax from:
Plant regulatory differences (b)	(19.3)		(5.2)		(1.5)
Amortization of excess nonplant deferred taxes	(12.6)		—		—
Other tax credits, net NOL & tax credit allowances	(1.5)		(1.8)		(0.8)
Change in unrecognized tax benefits	(0.8)		0.7		0.4
Reversal of prior regulatory differences	—		(3.6)		—
Other, net	—		(0.5)		(0.7)
Effective income tax rate	(7.0)	%	16.8	%	24.6	%

(a)Prior periods have been reclassified to conform to current year presentation.

(b)Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions.

Components of income tax expense for years ended Dec. 31:

(Millions of Dollars)	2020		2019		2018
Current federal tax expense	$	25	$	6	$	8
Current state tax expense	6		5		2
Current change in unrecognized tax (benefit) expense	(1)		1		—
Deferred federal tax (benefit) expense	(37)		3		16
Deferred state tax expense	1		2		7
Deferred ITCs	(1)		(1)		(1)
Total income tax (benefit) expense	$	(7)	$	16	$	32

Components of deferred income tax expense as of Dec. 31:

(Millions of Dollars)	2020		2019		2018
Deferred tax expense excluding items below	$	9	$	17	$	24
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities	(45)		(12)		(1)
Deferred tax (benefit) expense	$	(36)	$	5	$	23

Components of net deferred tax liability as of Dec. 31:

(Millions of Dollars)	2020		2019 (a)
Deferred tax liabilities:
Difference between book and tax bases of property	$	324	$	304
Regulatory assets	32		50
Pension expense	12		14
Other	9		7
Total deferred tax liabilities	$	377	$	375
Deferred tax assets:
Regulatory liabilities	$	41	$	47
Tax credit carryforward	8		5
Environmental remediation	6		6
Other employee benefits	4		4
Rate refund	4		9
Deferred ITCs	3		3
Other	4		3
Total deferred tax assets	$	70	$	77
Net deferred tax liability	$	307	$	298

(a) Prior periods have been reclassified to conform to current year presentation.

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Fair Value of Financial Assets and Liabilities

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

Fair Value Measurements

Accounting guidance for fair value measurements and disclosures provides a single definition of fair value and requires disclosures about assets and liabilities measured at fair value. A hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value is established by this guidance.

•Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are highly liquid and actively traded instruments with quoted prices.

•Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts, or priced with models using highly observable inputs.

•Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 are those valued with models requiring significant management judgment or estimation.

Specific valuation methods include:

Cash equivalents — The fair values of cash equivalents are generally based on cost plus accrued interest; money market funds are measured using quoted NAV.

Interest rate derivatives — The fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts.

Commodity derivatives — The methods used to measure the fair value of commodity derivative forwards and options utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. 

When contractual settlements relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable forecasts of forward prices and volatilities on a valuation is evaluated, and may result in Level 3 classification.

Derivative Instruments Fair Value Measurements

NSP-Wisconsin enters into derivative instruments, including forward contracts, futures, swaps and options, for trading purposes and to manage risk in connection with changes in interest rates and utility commodity prices.

Interest Rate Derivatives — NSP-Wisconsin may enter into various instruments that effectively fix the yield or price on a specified benchmark interest rate for an anticipated debt issuance for a specific period. These derivative instruments are generally designated as cash flow hedges for accounting purposes. As of Dec. 31, 2020 and 2019 there were no interest rate derivatives designated as cash flow hedges, respectively.

Commodity Derivatives — NSP-Wisconsin may enter into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations, as well as for trading purposes. This could include the purchase or sale of natural gas to generate electric energy and natural gas for resale.

Consideration of Credit Risk and Concentrations — NSP-Wisconsin continuously monitors the creditworthiness of counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. Impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented on the consolidated balance sheets.

Impact of Derivative Activities on Income — Changes in the fair value of natural gas commodity derivatives resulted in net losses of $1 million, for the years ended Dec. 31, 2020 and 2019, respectively and immaterial net losses for the year ended Dec. 31, 2018, recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

During the years ended Dec. 31, 2020 and 2019, $1 million of natural gas commodity derivatives settlement losses were recognized, respectively, and immaterial settlement gains for the year ended Dec. 31, 2018, were recognized subject to purchased natural gas cost recovery mechanisms, which result in reclassifications of derivative settlement gains and losses out of income to a regulatory asset or liability, as appropriate.

NSP-Wisconsin had no derivative instruments designated as fair value hedges during the years ended Dec. 31, 2020, 2019 and 2018.

Recurring Fair Value Measurements — NSP-Wisconsin’s derivative assets measured at fair value on a recurring basis were as follows:

	Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	1	$	—	$	1	$	—	$	1

(a)NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2020. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)Included in prepayments and other current assets balance of $7 million at Dec. 31, 2020 on the consolidated balance sheets.

	Dec. 31, 2019
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	1	$	—	$	1	$	—	$	1

(a)NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2019. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)Included in prepayments and other current assets balance of $5 million at Dec. 31, 2019 on the consolidated balance sheets.

Fair Value of Long-Term Debt

As of Dec. 31, other financial instruments for which the carrying amount did not equal fair value:

	2020				2019
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	906	$	1,124	$	808	$	924

Fair value of NSP-Wisconsin’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of Dec. 31, 2020 and 2019, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

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Benefit Plans and Other Postretirement Benefits

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Benefit Plans and Other Postretirement Benefits

9. Benefit Plans and Other Postretirement Benefits

Pension and Postretirement Health Care Benefits

Xcel Energy, which includes NSP-Wisconsin, has several noncontributory, qualified, defined benefit pension plans that cover almost all employees. All newly hired or rehired employees participate under the Cash Balance formula, which is based on pay credits using a percentage of annual eligible pay and annual interest credits. The average annual interest crediting rates for these plans was 1.78, 2.74 and 3.57 percent in 2020, 2019, and 2018, respectively. Some employees may participate under legacy formulas such as the traditional final average pay or pension equity. Xcel Energy’s policy is to fully fund into an external trust the actuarially determined pension costs subject to the limitations of applicable employee benefit and tax laws.

In addition to the qualified pension plans, Xcel Energy maintains a SERP and a nonqualified pension plan. The SERP is maintained for certain executives who participated in the plan in 2008, when the SERP was closed to new participants. The nonqualified pension plan provides benefits for compensation that is in excess of the limits applicable to the qualified pension plans, with distributions funded by Xcel Energy’s consolidated operating cash flows. Obligations of the SERP and nonqualified plan as of Dec. 31, 2020 and 2019 were $43 million and $39 million, respectively, of which $1 million was attributable to NSP-Wisconsin in both years. Xcel

Energy recognized net benefit cost for the SERP and nonqualified plans of $6 million and $4 million in 2020 and 2019, respectively, of which amounts attributable to NSP-Wisconsin were immaterial.

Xcel Energy, which includes NSPW, bases the investment-return assumption on expected long-term performance for each of the asset classes in its pension and postretirement health care portfolios. For pension assets, Xcel Energy considers the historical returns achieved by its asset portfolio over the past 20 years or longer period, as well as the long-term projected return levels. Xcel Energy and NSP-Wisconsin continually review their pension assumptions.

Pension cost determination assumes a forecasted mix of investment types over the long-term.

•Investment returns in 2020 were above the assumed level of 7.10%.

•Investment returns in 2019 were below the assumed level of 7.10%.

•Investment returns in 2018 were above the assumed level of 7.10%.

•In 2021, NSP-Wisconsin’s expected investment-return assumption is 6.60%.

Pension plan and postretirement benefit assets are invested in a portfolio according to Xcel Energy’s return, liquidity and diversification objectives to provide a source of funding for plan obligations and minimize contributions to the plan, within appropriate levels of risk. The principal mechanism for achieving these objectives is the asset allocation given the long-term risk, return, correlation and liquidity characteristics of each particular asset class. There were no significant concentrations of risk in any industry, index, or entity. Market volatility can impact even well-diversified portfolios and significantly affect the return levels achieved by the assets in any year.

Xcel Energy’s ongoing investment strategy is based on plan-specific investment recommendations that seek to minimize potential investment and interest rate risk as a plan’s funded status increases over time. The investment recommendations result in a greater percentage of long-duration fixed income securities being allocated to specific plans having relatively higher funded status ratios and a greater percentage of growth assets being allocated to plans having relatively lower funded status ratios.

Plan Assets

For each of the fair value hierarchy levels, NSP-Wisconsin’s pension plan assets measured at fair value:

	Dec. 31, 2020 (a)										Dec. 31, 2019 (a)
(Millions of Dollars)	Level 1		Level 2		Level 3		Measured at NAV		Total		Level 1		Level 2		Level 3		Measured at NAV		Total
Cash equivalents	$	8	$	—	$	—	$	—	$	8	$	6	$	—	$	—	$	—	$	6
Commingled funds	57		—		—		44		101		55		—		—		41		96
Debt securities	—		26		—		—		26		—		24		—		—		24
Equity securities	4		—		—		—		4		3		—		—		—		3
Other	1		—		—		—		1		(5)		—		—		—		(5)
Total	$	70	$	26	$	—	$	44	$	140	$	59	$	24	$	—	$	41	$	124

(a)See Note 8 for further information on fair value measurement inputs and methods.

NSP-Wisconsin has immaterial postretirement benefit plan assets that were measured at fair value at Dec. 31, 2020 and 2019.

No assets were transferred in or out of Level 3 for 2020. Immaterial assets were transferred in or out of Level 3 for 2019.

Funded Status — Benefit obligations for both pension and postretirement plans increased from Dec. 31, 2019 to Dec. 31, 2020, due primarily to decreases in discount rates used in actuarial valuations. Comparisons of the actuarially computed benefit obligation, changes in plan assets and funded status of the pension and postretirement health care plans for NSP-Wisconsin are as follows:

	Pension Benefits				Postretirement Benefits
(Millions of Dollars)	2020		2019		2020		2019
Change in Benefit Obligation:
Obligation at Jan. 1	$	144	$	140	$	13	$	13
Service cost	4		4		—		—
Interest cost	5		6		1		1
Actuarial loss	13		8		—		—
Benefit payments	(12)		(14)		(1)		(1)
Obligation at Dec. 31	$	154	$	144	$	13	$	13
Change in Fair Value of Plan Assets:
Fair value of plan assets at Jan. 1	$	124	$	110	$	—	$	—
Actual return on plan assets	21		21		—		—
Employer contributions	7		7		1		1
Benefit payments	(12)		(14)		(1)		(1)
Fair value of plan assets at Dec. 31	$	140	$	124	$	—	$	—
Funded status of plans at Dec. 31	$	(14)	$	(20)	$	(13)	$	(13)
Amounts recognized in the Consolidated Balance Sheet at Dec. 31:
Current liabilities	$	—	$	—	$	(1)	$	(1)
Noncurrent liabilities	(14)		(20)		(12)		(12)
Net amounts recognized	$	(14)	$	(20)	$	(13)	$	(13)

	Pension Benefits				Postretirement Benefits
Significant Assumptions Used to Measure Benefit Obligations:	2020		2019		2020		2019
Discount rate for year-end valuation	2.71	%	3.49	%	2.65	%	3.47	%
Expected average long-term increase in compensation level	3.75	%	3.75	%	N/A		N/A
Mortality table	Pri-2012		Pri-2012		Pri-2012		Pri-2012
Health care costs trend rate — initial: Pre-65	N/A		N/A		5.50	%	6.00	%
Health care costs trend rate — initial: Post-65	N/A		N/A		5.00	%	5.10	%
Ultimate trend assumption — initial: Pre-65	N/A		N/A		4.50	%	4.50	%
Ultimate trend assumption — initial: Post-65	N/A		N/A		4.50	%	4.50	%
Years until ultimate trend is reached	N/A		N/A		5		3

Accumulated benefit obligation for the pension plan was $141 million and $132 million as of Dec. 31, 2020 and 2019, respectively.

Net Periodic Benefit Cost (Credit) — Net periodic benefit cost (credit), other than the service cost component, is included in other expense in the consolidated statements of income.

Components of net periodic benefit cost (credit) and amounts recognized in other comprehensive income and regulatory assets and liabilities:

	Pension Benefits									Postretirement Benefits
(Millions of Dollars)	2020			2019			2018			2020			2019			2018
Service cost	$	4		$	4		$	5		$	—		$	—		$	—
Interest cost	5			6			5			1			1			1
Expected return on plan assets	(8)			(8)			(9)			—			—			—
Amortization of net loss	5			4			6			—			—			—
Settlement charge (a)	—			—			7			—			—			—
Net periodic pension cost	$	6		$	6		$	14		$	1		$	1		$	1
Effects of regulation	7			—			(3)			—			—			—
Net benefit cost recognized for financial reporting	$	13		$	6		$	11		$	1		$	1		$	1
Significant Assumptions Used to Measure Costs:
Discount rate	3.49		%	4.31		%	3.63		%	3.47		%	4.32		%	3.62		%
Expected average long-term increase in compensation level	3.75			3.75			3.75			—			—			—
Expected average long-term rate of return on assets	7.10			7.10			7.10			4.50			4.50			5.30

(a)A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2018, as a result of lump-sum distributions during the 2018 plan year, NSP-Wisconsin recorded a total pension settlement charge of $7 million in 2018, a total of $2 million of that amount was recorded in the income statement in 2018. There were no settlement charges recorded to the qualified pension plans in 2020 and 2019.

	Pension Benefits				Postretirement Benefits
(Millions of Dollars)	2020		2019		2020		2019
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost:
Net loss	$	60	$	64	$	7	$	7
Prior service credit	—		—		(1)		(1)
Total	$	60	$	64	$	6	$	6
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates:
Current regulatory assets	$	4	$	4	$	—	$	—
Noncurrent regulatory assets	56		60		6		6
Total	$	60	$	64	$	6	$	6

Measurement date Dec. 31, 2020 Dec. 31, 2019 Dec. 31, 2020 Dec. 31, 2019

Cash Flows — Funding requirements can be impacted by changes to actuarial assumptions, actual asset levels and other calculations prescribed by the requirements of income tax and other pension-related regulations. Required contributions were made in 2018-2021 to meet minimum funding requirements.

Total voluntary and required pension funding contributions across all four of Xcel Energy’s pension plans were as follows:

•$125 million in January 2021, of which $5 million was attributable to NSP-Wisconsin.

•$150 million in 2020, of which $7 million was attributable to NSP-Wisconsin.

•$154 million in 2019, of which $7 million was attributable to NSP-Wisconsin.

•$150 million in 2018, of which $10 million was attributable to NSP-Wisconsin.

The postretirement health care plans have no funding requirements other than fulfilling benefit payment obligations, when claims are presented and approved. Additional cash funding requirements are prescribed by certain state and federal rate regulatory authorities. Xcel Energy’s voluntary postretirement funding contributions were as follows:

•$10 million in January 2021, of which $1 million is attributable to NSP-Wisconsin.

•$11 million in 2020, of which $1 million, was attributable to NSP-Wisconsin.

•$15 million in 2019, of which $1 million was attributable to NSP-Wisconsin.

•$11 million in 2018, of which an immaterial amount was attributable to NSP-Wisconsin.

Target asset allocations:

	Pension Benefits				Postretirement Benefits
	2020		2019		2020		2019
Domestic and international equity securities	35	%	37	%	15	%	15	%
Long-duration fixed income and interest rate swap securities	35		30		—		—
Short-to-intermediate fixed income securities	13		14		72		72
Alternative investments	15		17		9		9
Cash	2		2		4		4
Total	100	%	100	%	100	%	100	%

The asset allocations above reflect target allocations approved in the calendar year to take effect in the subsequent year

Plan Amendments — In 2019, the Pension Protection Act measurement concept was extended beyond 2019 for NSP bargaining terminations and retirements to Dec. 31, 2022.

In 2020 and 2018, there were no significant plan amendments made which affected the postretirement benefit obligation.

Projected Benefit Payments

NSP-Wisconsin’s projected benefit payments:

(Millions of Dollars)	Projected Pension Benefit Payments		Gross Projected Postretirement Health Care Benefit Payments		Expected Medicare Part D Subsidies		Net Projected Postretirement Health Care Benefit Payments
2021	$	13	$	1	$	—	$	1
2022	12		1		—		1
2023	12		1		—		1
2024	12		1		—		1
2025	12		1		—		1
2026-2030	57		3		—		3

Defined Contribution Plans

Xcel Energy, which includes NSP-Wisconsin, maintains 401(k) and other defined contribution plans that cover most employees. The expense to these plans for NSP-Wisconsin was approximately $2 million in 2020, 2019 and 2018.

Multiemployer Plans

NSP-Wisconsin contributes to several union multiemployer pension plans, none of which are individually significant. These plans provide pension benefits to certain union employees who may perform services for multiple employers and do not participate in the NSP-Wisconsin sponsored pension plans. Contributing to these types of plans creates risk that differs from providing benefits under NSP-Wisconsin sponsored plans, in that if another participating employer ceases to contribute to a multiemployer plan, additional unfunded obligations may need to be funded over time by remaining participating employers.

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Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Rate MattersMISO ROE Complaints —

Environmental

New and changing federal and state environmental mandates can create financial liabilities for NSP-Wisconsin, which are normally recovered through the regulated rate process.

Site Remediation

Various federal and state environmental laws impose liability where hazardous substances or other regulated materials have been released to the environment. NSP-Wisconsin may sometimes pay all or a portion of the cost to remediate sites where past activities of NSP-Wisconsin’s predecessors or other parties have caused environmental contamination. Environmental contingencies could arise from various situations, including sites of former MGPs; and third-party sites, such as landfills, for which NSP-Wisconsin is alleged to have sent wastes to that site.

MGP, Landfill and Disposal Sites

Ashland MGP Site — NSP-Wisconsin was named a responsible party for contamination at the Ashland/Northern States Power Lakefront Superfund Site (the Site) in Ashland, Wisconsin. Remediation was completed in 2019 and restoration activities were completed in 2020. Groundwater treatment activities will continue for many years.

The cost estimate for remediation and restoration of the entire site is approximately $199 million. At Dec. 31, 2020 and 2019, NSP-Wisconsin had a total liability of $19 million and $23 million, respectively, for the entire site.

NSP-Wisconsin has deferred the unrecovered portion of the estimated Site remediation and restoration costs as a regulatory asset. The PSCW has authorized NSP-Wisconsin rate recovery for all remediation and restoration costs incurred at the Site and application of a 3% carrying charge to the regulatory asset.

In January 2021, the EPA confirmed that NSP-Wisconsin completed its work on the soils and sediments at the Site and all that remains is the long-term groundwater pump and treat program.

In addition to the Ashland Site, NSP-Wisconsin is currently investigating, remediating or performing post-closure actions at one other MGP, landfill or other disposal site across its service territory.

NSP-Wisconsin has recognized its best estimate of costs/liabilities that will result from final resolution of these issues, however, the outcome and timing is unknown. In addition, there may be insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of costs incurred.

Environmental Requirements — Water and Waste

Federal CWA WOTUS Rule — In April 2020, the EPA and U.S. Army Corps of Engineers (“Agencies”) replaced the 2015 WOTUS rule and narrowed the definition of WOTUS (“2020 WOTUS Rule”). The new definition simplifies the process whether waters are subject to CWA jurisdiction and streamlines the permitting process. NSP-Wisconsin does not anticipate that compliance costs will be material.

Federal CWA Section 316(b) — The federal CWA requires the EPA to regulate cooling water intake structures to assure that these structures reflect the best technology available for minimizing impingement and entrainment of aquatic species. NSP-Wisconsin estimates the likely cost for complying with impingement requirements is approximately $4 million, to be incurred between 2021 and 2028, while the total cost of entrainment improvements is anticipated to be immaterial. NSP-Wisconsin believes two plants could be required to make improvements to reduce impingement and entrainment. The exact total cost of the impingement and entrainment improvements is uncertain but could be up to $4 million. NSP-Wisconsin anticipates these costs will be fully recoverable through regulatory mechanisms.

ROs — AROs have been recorded for NSP-Wisconsin’s assets.

NSP-Wisconsin’s AROs were as follows:

	2020
(Millions of Dollars)	Jan. 1, 2020		Cash Flow Revisions (a)		Dec. 31, 2020 (b)
Electric
Distribution	$	5	$	—	$	5
Steam, hydro and other production	4		4		8
Natural gas
Distribution	9		—		9
Total liability (c)	$	18	$	4	$	22

(a)In 2020, AROs were revised for changes in timing and estimates of cash flows. Revisions in steam, hydro and other production AROs primarily related to changes in cost estimates for remediation of ash containment facilities.

(b)There were no ARO amounts incurred or settled in 2020.

(c)Included in other long-term liabilities balance in the consolidated balance sheet.

	2019
(Millions of Dollars)	Jan. 1, 2019		Accretion		Cash Flow Revisions		Dec. 31, 2019 (a)
Electric
Distribution	$	5	$	—	$	—	$	5
Steam, hydro and other production	4		—		—		4
Natural gas
Distribution	9		1		(1)		9
Total liability (b)	$	18	$	1	$	(1)	$	18

(a)There were no ARO amounts incurred or settled in 2019.

(b)Included in other long-term liabilities balance in the consolidated balance sheet.

Indeterminate AROs — Outside of the recorded asbestos AROs, other plants or buildings may contain asbestos due to the age of many of NSP-Wisconsin’s facilities, but no confirmation or measurement of the cost of removal could be determined as of Dec. 31, 2020. Therefore, an ARO has not been recorded for these facilities.

Joint Operating System

The electric production and transmission system of NSP-Wisconsin is managed as the NSP System. The electric production and transmission costs of the entire NSP System are shared by NSP-Minnesota and NSP-Wisconsin. A FERC approved agreement between the two companies, called the Interchange Agreement, provides for the sharing of all costs of generation and transmission facilities of the system, including capital costs. Such costs include current and potential obligations of NSP-Minnesota related to its nuclear generating facilities.

NSP-Minnesota’s public liability for claims from any nuclear incident is limited to $13.8 billion under the Price-Anderson amendment to the Atomic Energy Act. NSP-Minnesota has secured $450 million of coverage for its public liability exposure with a pool of insurance companies. The remaining $13.3 billion of exposure is funded by the Secondary Financial Protection Program, available from assessments by the federal government.

NSP-Minnesota is subject to assessments of up to $138 million per reactor-incident for each of its three licensed reactors, for public liability arising from a nuclear incident at any licensed nuclear facility in the United States. The maximum funding requirement is $21 million per reactor-incident during any one year. Maximum assessments are subject to inflation adjustments by the NRC and state premium taxes. The NRC’s last adjustment was effective November 2018.

NSP-Minnesota purchases insurance for property damage and site decontamination cleanup costs from NEIL and EMANI. The coverage limits are $2.8 billion for each of NSP-Minnesota’s two nuclear plant sites. NEIL also provides business interruption insurance coverage up to $350 million, including the cost of replacement power during prolonged accidental outages of nuclear generating units. Premiums are expensed over the policy term.

All companies insured with NEIL are subject to retroactive premium adjustments if losses exceed accumulated reserve funds. Capital has been accumulated in the reserve funds of NEIL and EMANI to the extent that NSP-Minnesota would have no exposure for retroactive premium assessments in case of a single incident under the business interruption and the property damage insurance coverage. NSP-Minnesota could be subject to annual maximum assessments of approximately $11 million for business interruption insurance and $34 million for property damage insurance if losses exceed accumulated reserve funds.

NSP-Wisconsin has entered into various long-term commitments for the purchase and delivery of a significant portion of its refuse-derived fuel/wood and natural gas requirements. These contracts expire between 2021 and 2029. NSP-Wisconsin is required to pay additional amounts depending on actual quantities shipped under these agreements.

As NSP-Wisconsin does not have an automatic electric fuel adjustment clause for Wisconsin retail customers, NSP-Wisconsin utilizes deferred accounting treatment for future rate recovery or refund when fuel costs differ from the amount included in rates by more than 2% on an annual basis, as determined by the PSCW after an opportunity for a hearing and an earnings test based on NSP-Wisconsin’s authorized ROE.

Estimated minimum purchases under these contracts as of Dec. 31, 2020:

(Millions of Dollars)	Refuse-derived fuel/wood		Natural gas supply		Natural gas storage and transportation
2021	$	5	$	8	$	16
2022	1		—		14
2023	1		—		11
2024	1		—		9
2025	1		—		8
Thereafter	3		—		14
Total (a)	$	12	$	8	$	72

(a)Excludes additional amounts allocated to NSP-Wisconsin through intercompany charges.

Additional expenditures for fuel and natural gas storage and transportation will be required to meet expected future electric generation and natural gas needs.

VIEs

NSP-Wisconsin has entered into limited partnerships for the construction and operation of affordable rental housing developments, which qualify for low-income housing tax credits. NSP-Wisconsin has determined the low-income housing partnerships to be VIEs primarily due to contractual arrangements within each limited partnership that establishes sharing of ongoing voting control and profits and losses that do not align with the partners’ proportional equity ownership.

NSP-Wisconsin has the power to direct the activities that most significantly impact these entities’ economic performance. Therefore, NSP-Wisconsin consolidates these limited partnerships in its consolidated financial statements. NSP-Wisconsin’s risk of loss for these partnerships is limited to its capital contributions, adjusted for any distributions and its share of undistributed profits and losses; no significant additional financial support has been, or is required to be provided to the limited partnerships by NSP-Wisconsin.

Amounts reflected in NSP-Wisconsin’s consolidated balance sheets for low-income housing limited partnerships include the following:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Current assets	$	—	$	—
Property, plant and equipment, net	1		1
Other noncurrent assets	—		—
Total assets	$	1	$	1
Current liabilities	$	—	$	—
Mortgages and other long-term debt payable	1		1
Other noncurrent liabilities	—		—
Total liabilities	$	1	$	1

Other

Guarantees — NSP-Wisconsin provides a guarantee for payment of customer loans related to NSP-Wisconsin’s farm rewiring program. NSP-Wisconsin’s exposure under the guarantee is based upon the net liability under the agreement. The guarantee issued by NSP-Wisconsin limits the exposure of NSP-Wisconsin to a maximum amount stated in the guarantee. The guarantee contains no recourse provisions and requires no collateral.

Guarantee issued and outstanding for NSP-Wisconsin:

(Millions of Dollars)	Guarantor	Guarantee Amount		Current Exposure		Triggering Event
Guarantee of customer loans for the Farm Rewiring Program (a)	NSP-Wisconsin	$	1	$	—	(b)

(a)As of Dec. 31, 2020, no claims were outstanding against the guarantee.

(b)The debtor becomes the subject of bankruptcy or other insolvency proceedings.

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Other Comprehensive Income

12 Months Ended

Dec. 31, 2020

Stockholders' Equity Note [Abstract]

Other Comprehensive Income

Changes in accumulated other comprehensive loss, net of tax, for the years ended Dec. 31:

	Gains and Losses on Cash Flow Hedges
(Millions of Dollars)	2020		2019
Accumulated other comprehensive loss at Jan. 1	$	—	$	—
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $—) (a)	—		—
Net current period other comprehensive income (loss)	—		—
Accumulated other comprehensive loss at Dec. 31	$	—	$	—

(a)Included in interest charges.

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Segments and Related Information

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Segment Information

NSP-Wisconsin evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment.

NSP-Wisconsin has the following reportable segments:

•Regulated Electric — The regulated electric utility segment generates electricity which is transmitted and distributed in Wisconsin and Michigan.

•Regulated Natural Gas — The regulated natural gas utility segment purchases, transports, stores and distributes natural gas in portions of Wisconsin and Michigan.

NSP-Wisconsin also presents All Other, which includes operating segments with revenues below the necessary quantitative thresholds. Those operating segments primarily include investments in rental housing projects that qualify for low-income housing tax credits.

Asset and capital expenditure information is not provided for NSP-Wisconsin’s reportable segments. As an integrated electric and natural gas utility, NSP-Wisconsin operates significant assets that are not dedicated to a specific business segment. Reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations, which may not necessarily reflect the assets required for the operation of the business segments on a stand-alone basis.

Certain costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators across each segment. In addition, a general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising.

NSP-Wisconsin’s segment information:

(Millions of Dollars)	2020		2019		2018
Regulated Electric
Operating revenues - external (a)	$	855	$	845	$	879
Intersegment revenue	1		—		—
Total revenues	$	856	$	845	$	879
Depreciation and amortization	108		109		98
Interest charges and financing costs	34		34		32
Income tax expense	12		13		28
Net income	98		68		85
Regulated Natural Gas
Total revenues	$	119	$	136	$	142
Depreciation and amortization	48		29		28
Interest charges and financing costs	4		4		3
Income tax (benefit) expense	(20)		2		5
Net income	7		10		13
All Other
Total revenues (a)	$	—	$	—	$	1
Income tax expense (benefit)	1		1		(1)
Net income	2		1		—
Consolidated Total
Total revenues (a)	$	975	$	981	$	1,022
Reconciling eliminations	(1)		—		—
Total operating revenues	$	974	$	981	$	1,022
Depreciation and amortization	156		138		126
Interest charges and financing costs	38		38		35
Income tax (benefit) expense	(7)		16		32
Net income	107		79		98

(a)    Operating revenues include $168 million, $177 million and $158 million of intercompany revenue for the years ended Dec. 31, 2020, 2019 and 2018, respectively. See Note 12 for further information.

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Related Party Transactions

12 Months Ended

Dec. 31, 2020

Related Party Transactions [Abstract]

Related Party Transactions

Xcel Energy Services Inc. provides management, administrative and other services for the subsidiaries of Xcel Energy Inc., including NSP-Wisconsin. The services are provided and billed to each subsidiary in accordance with service agreements executed by each subsidiary. NSP-Wisconsin uses services provided by Xcel Energy Services Inc. whenever possible. Costs are charged directly to the subsidiary and are allocated if they cannot be directly assigned.

Xcel Energy Inc., NSP-Minnesota, NSP-Wisconsin, PSCo and SPS have established a utility money pool arrangement.

The electric production and transmission costs of the entire NSP System are shared by NSP-Minnesota and NSP-Wisconsin. The Interchange Agreement provides for the sharing of all costs of generation and transmission facilities of the system, including capital costs.

Significant affiliate transactions among the companies and related parties including billings under the Interchange Agreement for the years ended Dec. 31:

(Millions of Dollars)	2020		2019		2018
Operating revenues:
Electric	$	168	$	177	$	158
Operating expenses:
Purchased power	379		394		411
Transmission expense	61		64		63
Natural gas purchased for resale	1		1		—
Other operating expenses — paid to Xcel Energy Services Inc.	92		87		87

Accounts receivable and payable with affiliates at Dec. 31 were:

	2020				2019
(Millions of Dollars)	Accounts Receivable		Accounts Payable		Accounts Receivable		Accounts Payable
NSP-Minnesota	$	—	$	6	$	—	$	8
PSCo	1		—		—		—
Other subsidiaries of Xcel Energy Inc.	9		9		—		11
	$	10	$	15	$	—	$	19

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Summarized Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Summarized Quarterly Financial Data (Unaudited)

	Quarter Ended
(Millions of Dollars)	March 31, 2020		June 30, 2020		Sept. 30, 2020		Dec. 31, 2020
Operating revenues	$	257	$	218	$	251	$	248
Operating income	41		23		46		31
Net income	34		12		40		21

	Quarter Ended
(Millions of Dollars)	March 31, 2019		June 30, 2019		Sept. 30, 2019		Dec. 31, 2019
Operating revenues	$	276	$	229	$	244	$	232
Operating income	42		22		48		19
Net income	24		9		29		17

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Schedule II, Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2019

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II, Valuation and Qualifying Accounts

NSP-Wisconsin and Subsidiaries Valuation and Qualifying Accounts Years Ended Dec. 31

	Allowance for bad debts
(Millions of Dollars)	2020		2019		2018
Balance at Jan. 1	$	6	$	6	$	5
Additions charged to costs and expenses	7		7		4
Additions charged to other accounts (a)	1		2		1
Deductions from reserves (b)	(6)		(9)		(4)
Balance at Dec. 31	$	8	$	6	$	6

(a)Recovery of amounts previously written-off.

(b)Deductions related primarily to bad debt write-offs.

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Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Business and System of Accounts

General — NSP-Wisconsin is engaged in the regulated generation, transmission, distribution and sale of electricity and in the regulated purchase, transportation, distribution and sale of natural gas.NSP-Wisconsin’s consolidated financial statements are presented in accordance with GAAP. All of NSP-Wisconsin’s underlying accounting records also conform to the FERC uniform system of accounts or to systems required by various state regulatory commissions. Certain amounts in the consolidated financial statements or notes have been reclassified for comparative purposes; however, such reclassifications did not affect net income, total assets, liabilities, equity or cash flows.

Principles of Consolidation

NSP-Wisconsin’s consolidated financial statements include its wholly-owned subsidiaries and VIEs for which it is the primary beneficiary. In the consolidation process, all intercompany transactions and balances are eliminated. NSP-Wisconsin has investments in certain transmission facilities jointly owned with nonaffiliated utilities.

NSP-Wisconsin’s proportionate share of jointly owned facilities is recorded as property, plant and equipment on the consolidated balance sheets and NSP-Wisconsin’s proportionate share of the operating costs associated with these facilities is included in its consolidated statements of income.

Subsequent Events

NSP-Wisconsin has evaluated events occurring after Dec. 31, 2020 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation.

Use of Estimates

Use of Estimates — NSP-Wisconsin uses estimates based on the best information available in recording transactions and balances resulting from business operations. Estimates are used on items such as plant depreciable lives or potential disallowances, AROs, certain regulatory assets and liabilities, tax provisions, uncollectible amounts, environmental costs, unbilled revenues, jurisdictional fuel and energy cost allocations and actuarially determined benefit costs. Recorded estimates are revised when better information becomes available or actual amounts can be determined. Revisions can affect operating results.

Regulatory Accounting

Regulatory Accounting — NSP-Wisconsin accounts for income and expense items in accordance with accounting guidance for regulated operations. Under this guidance:

•Certain costs, which would otherwise be charged to expense or other comprehensive income, are deferred as regulatory assets based on the expected ability to recover the costs in future rates.

•Certain credits, which would otherwise be reflected as income or other comprehensive income, are deferred as regulatory liabilities based on the expectation the amounts will be returned to customers in future rates or because the amounts were collected in rates prior to the costs being incurred.

Estimates of recovering deferred costs and returning deferred credits are based on specific ratemaking decisions or precedent for each item. Regulatory assets and liabilities are amortized consistent with the treatment in the rate setting process.

If changes in the regulatory environment occur, NSP-Wisconsin may no longer be eligible to apply this accounting treatment and may be required to eliminate regulatory assets and liabilities from its balance sheets. Such changes could have a material effect on NSP-Wisconsin’s results of operations, financial condition and cash flows.

See Note 4 for further information.

Income Taxes

Income Taxes — NSP-Wisconsin accounts for income taxes using the asset and liability method, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. NSP-Wisconsin defers income taxes for all temporary differences between pretax financial and taxable income and between the book and tax bases of assets and liabilities. NSP-Wisconsin uses rates that are scheduled to be in effect when the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the period that includes the enactment date.

The effects of NSP-Wisconsin’s tax rate changes are generally subject to a normalization method of accounting. Therefore, the revaluation of most of its net deferred taxes upon a tax rate reduction results in the establishment of a net regulatory liability, which would be refundable to utility customers over the remaining life of the related assets. NSP-Wisconsin anticipates that a tax rate increase would result in the establishment of a regulatory asset, subject to regulatory approval.

Reversal of certain temporary differences are accounted for as current income tax expense due to the effects of past regulatory practices when deferred taxes were not required to be recorded due to the use of flow through accounting for ratemaking purposes. Tax credits are recorded when earned unless there is a requirement to defer the benefit and amortize it over the book depreciable lives of the related property. The requirement to defer and amortize tax credits only applies to federal ITCs related to public utility property. Utility rate regulation also has resulted in the recognition of regulatory assets and liabilities related to income taxes. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized.

NSP-Wisconsin follows the applicable accounting guidance to measure and disclose uncertain tax positions that it has taken or expects to take in its income tax returns. NSP-Wisconsin recognizes a tax position in its consolidated financial statements when it is more likely than not that the position will be sustained upon examination based on the technical merits of the position. Recognition of changes in uncertain tax positions are reflected as a component of income tax expense.

NSP-Wisconsin reports interest and penalties related to income taxes within other (expense) income or interest charges in the consolidated statements of income.

Xcel Energy Inc. and its subsidiaries, including NSP-Wisconsin, file consolidated federal income tax returns as well as consolidated or separate state income tax returns. Federal income taxes paid by Xcel Energy Inc. are allocated to its subsidiaries based on separate company computations. A similar allocation is made for state income taxes paid by Xcel Energy Inc. in connection with consolidated state filings. Xcel Energy Inc. also allocates its own income tax benefits to its direct subsidiaries.

See Note 7 for further information.

Property, Plant and Equipment and Depreciation

Property, Plant and Equipment and Depreciation in Regulated Operations — Property, plant and equipment is stated at original cost. The cost of plant includes direct labor and materials, contracted work, overhead costs and AFUDC. The cost of plant retired is charged to accumulated depreciation and amortization. Amounts recovered in rates for future removal costs are recorded as regulatory liabilities. Significant additions or improvements extending asset lives are capitalized, while repairs and maintenance costs are charged to expense as incurred. Maintenance and replacement of items determined to be less than a unit of property are charged to operating expenses as incurred. Planned maintenance activities are charged to operating expense unless the cost represents the acquisition of an additional unit of property or the replacement of an existing unit of property.

Property, plant and equipment is tested for impairment when it is determined that the carrying value of the assets may not be recoverable. A loss is recognized in the current period if it becomes probable that part of a cost of a plant under construction or recently completed plant will be disallowed for recovery from customers and a reasonable estimate of the disallowance can be made. For investments in property, plant and equipment that are abandoned and not expected to go into service, incurred costs and related deferred tax amounts are compared to the discounted estimated future rate recovery, and a loss is recognized, if necessary.

NSP-Wisconsin records depreciation expense using the straight-line method over the plant’s useful life. Actuarial life studies are performed and submitted to the state and federal commissions for review. Upon acceptance by the various commissions, the resulting lives and net salvage rates are used to calculate depreciation. Plant removal costs are recovered in rates as authorized by the appropriate regulatory entities. The amount of removal costs are based on current factors used in existing depreciation rates. Depreciation expense, expressed as a percentage of average depreciable property, was approximately 3.6% in 2020, 3.6% in 2019 and 3.5% in 2018.

See Note 3 for further information.

Asset Retirement Obligations

AROs — NSP-Wisconsin accounts for AROs under accounting guidance that requires a liability for the fair value of an ARO to be recognized in the period in which it is incurred if it can be reasonably estimated, with the offsetting associated asset retirement costs capitalized as a long-lived asset. The liability is generally increased over time by applying the effective interest method of accretion, and the capitalized costs are depreciated over the useful life of the long-lived asset. Changes resulting from revisions to the timing or amount of expected asset retirement cash flows are recognized as an increase or a decrease in the ARO.

See Note 10 for further information.

Benefit Plans and Other Postretirement Benefits

Benefit Plans and Other Postretirement Benefits — NSP-Wisconsin maintains pension and postretirement benefit plans for eligible employees. Recognizing the cost of providing benefits and measuring the projected benefit obligation of these plans requires management to make various assumptions and estimates.

Certain unrecognized actuarial gains and losses and unrecognized prior service costs or credits are deferred as regulatory assets and liabilities, rather than recorded as other comprehensive income, based on regulatory recovery mechanisms.

See Note 9 for further information.

Environmental Costs

Environmental Costs — Environmental costs are recorded when it is probable NSP-Wisconsin is liable for remediation costs and the liability can be reasonably estimated. Costs are deferred as a regulatory asset if it is probable that the costs will be recovered from customers in future rates. Otherwise, the costs are expensed. If an environmental expense is related to facilities currently in use, such as emission-control equipment, the cost is capitalized and depreciated over the life of the plant.

Estimated remediation costs are regularly adjusted as estimates are revised and remediation proceeds. If other participating potentially responsible parties exist and acknowledge their potential involvement with a site, costs are estimated and recorded only for NSP-Wisconsin’s expected share of the cost.

Future costs of restoring sites are treated as a capitalized cost of plant retirement. The depreciation expense levels recoverable in rates include a provision for removal expenses. Removal costs recovered in rates before the related costs are incurred are classified as a regulatory liability.

See Note 10 for further information.

Revenue From Contracts With Customers

Revenue from Contracts with Customers — Performance obligations related to the sale of energy are satisfied as energy is delivered to customers. NSP-Wisconsin recognizes revenue that corresponds to the price of the energy delivered to the customer. The measurement of energy sales to customers is generally based on the reading of their meters, which occurs systematically throughout the month. At the end of each month, amounts of energy delivered to customers since the date of the last meter reading are estimated, and the corresponding unbilled revenue is recognized.

NSP-Wisconsin does not recognize a separate financing component of its collections from customers as contract terms are short-term in nature. NSP-Wisconsin presents its revenues net of any excise or sales taxes or fees.

NSP-Wisconsin has various rate-adjustment mechanisms that provide for the recovery of natural gas, electric fuel and purchased energy costs. Cost-adjustment tariffs may increase or decrease the level of revenue collected from customers and are revised periodically for differences between the total amount collected under the clauses and the costs incurred. When applicable, fuel cost over-recoveries (the excess of fuel revenue billed to customers over fuel costs incurred) are deferred as regulatory liabilities and under-recoveries (the excess of fuel costs incurred over fuel revenues billed to customers) are deferred as regulatory assets. NSP-Wisconsin must submit a forward looking fuel cost plan annually for approval by the PSCW. The rules also allow for deferral of any under-recovery or over-recovery of fuel costs in excess of a 2% annual tolerance band, for future rate recovery or refund, subject to PSCW approval.

Cash and Cash Equivalents

Cash and Cash Equivalents — NSP-Wisconsin considers investments in instruments with a remaining maturity of three months or less at the time of purchase to be cash equivalents.

Accounts Receivable and Allowance for Bad Debts

Accounts Receivable and Allowance for Bad Debts — Accounts receivable are stated at the actual billed amount net of an allowance for bad debts. NSP-Wisconsin establishes an allowance for uncollectible receivables based on a policy that reflects its expected exposure to the credit risk of customers. As of Dec. 31, 2020 and 2019, the allowance for bad debts was $8 million and $6 million, respectively.

Inventory

Inventory — Inventory is recorded at average cost and consisted of the following:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Inventories
Materials and supplies	$	7	$	7
Fuel	4		4
Natural gas	4		5
Total inventories	$	15	$	16

Fair Value Measurements

Fair Value Measurements — NSP-Wisconsin presents cash equivalents, interest rate derivatives and commodity derivatives at estimated fair values in its consolidated financial statements. Cash equivalents are recorded at cost plus accrued interest; money market funds are measured using quoted NAVs. For interest rate derivatives, quoted prices based primarily on observable market interest rate curves are used to establish fair value. For commodity derivatives, the most observable inputs available are generally used to determine the fair value of each contract. In the absence of a quoted price, NSP-Wisconsin may use quoted prices for similar contracts or internally prepared valuation models to determine fair value.

For the pension and postretirement plan assets published trading data and pricing models, generally using the most observable inputs available, are utilized to estimate fair value for each security.

See Notes 8 and 9 for further information.

Derivative Instruments

Derivative Instruments — NSP-Wisconsin uses derivative instruments in connection with its utility commodity price and interest rate activities, including forward contracts, futures, swaps and options. Any derivative instruments not qualifying for the normal purchases and normal sales exception are recorded on the consolidated balance sheets at fair value as derivative instruments. Classification of changes in fair value for those derivative instruments is dependent on the designation of a qualifying hedging relationship. Changes in fair value of derivative instruments not designated in a qualifying hedging relationship are reflected in current earnings or as a regulatory asset or liability. Classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

Interest rate hedging transactions are recorded as a component of interest expense. NSP-Wisconsin is allowed to recover in electric or natural gas rates the costs of certain financial instruments purchased to reduce commodity cost volatility.

Normal Purchases and Normal Sales — NSP-Wisconsin enters into contracts for purchases and sales of commodities for use in its operations. At inception, contracts are evaluated to determine whether a derivative exists and/or whether an instrument may be exempted from derivative accounting if designated as a normal purchase or normal sale.

See Note 8 for further information.

AFUDC

AFUDC — AFUDC represents the cost of capital used to finance utility construction activity. AFUDC is computed by applying a composite financing rate to qualified CWIP. The amount of AFUDC capitalized as a utility construction cost is credited to other nonoperating income (for equity capital) and interest charges (for debt capital). AFUDC amounts capitalized are included in NSP-Wisconsin’s rate base for establishing utility rates

Alternative revenue programs

Alternative Revenue — Certain rate rider mechanisms qualify as alternative revenue programs. These mechanisms arise from costs imposed upon the utility by action of a regulator or legislative body related to an environmental, public safety or other mandate. When certain criteria are met, including expected collection within 24 months, revenue is recognized equal to the revenue requirement, which may include return on rate base items and incentives. The mechanisms are revised periodically for differences between total amount collected and the revenue recognized, which may increase or decrease the level of revenue collected from customers. Alternative revenues arising from these programs are presented on a gross basis and disclosed separately from revenue from contracts with customers.

See Note 6 for further information.

Conservation Programs — NSP-Wisconsin participates in and funds conservation programs in its retail jurisdictions to assist customers in conserving energy and reducing peak demand on the electric and natural gas systems. NSP-Wisconsin recovers approved conservation program costs in base rate revenue.

For operations in the state of Wisconsin, NSP-Wisconsin is required to contribute 1.2% of its three-year average annual operating revenues to the statewide energy efficiency and renewable resource program Focus on Energy. Funding is collected through base rates, and there is no financial incentive provided to the utility. The PSCW has full oversight of Focus on Energy including auditing and verification of programs. The program portfolio is outsourced to a third-party administrator who subcontracts as necessary to implement programs.

Emission Allowances

Emission Allowances — Emission allowances are recorded at cost, including broker commission fees. The inventory accounting model is utilized for all emission allowances and sales of these allowances are included in electric revenues.

Renewable Energy Credits

RECs — Cost of RECs that are utilized for compliance is recorded as electric fuel and purchased power expense.Sales of RECs are recorded in electric revenues on a gross basis. Cost of these RECs are recorded in electric fuel and purchased power expense.

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Summary of Significant Accounting Policies Inventory (Tables)

12 Months Ended

Dec. 31, 2020

Balance Sheet Related Disclosure - Inventory [Abstract]

Public Utilities, Inventory

Inventory — Inventory is recorded at average cost and consisted of the following:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Inventories
Materials and supplies	$	7	$	7
Fuel	4		4
Natural gas	4		5
Total inventories	$	15	$	16

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Property Plant and Equipment Property Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Public Utility Property, Plant, and Equipment

Major classes of property, plant and equipment

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Property, plant and equipment, net
Electric plant	$	3,197	$	3,025
Natural gas plant	391		365
Common and other property	221		201
CWIP	71		83
Total property, plant and equipment	3,880		3,674
Less accumulated depreciation	(1,396)		(1,315)
Property, plant and equipment, net	$	2,484	$	2,359

Schedule of Jointly Owned Utility Plants

Jointly owned assets as of Dec. 31, 2020:

(Millions of Dollars, Except Percent Owned)	Plant in Service		Accumulated Depreciation		CWIP		Percent Owned
Electric transmission:
La Crosse, WI to Madison, WI	$	188	$	12	$	—	37	%
CapX2020	169		23		—		80
Total	$	357	$	35	$	—

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Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Assets

Components of regulatory assets:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2020				Dec. 31, 2019
Regulatory Assets			Current		Noncurrent		Current		Noncurrent
Environmental remediation costs	1, 10	Various	$	13	$	94	$	35	$	108
Pension and retiree medical obligations	9	Various	4		67		12		70
State commission adjustments		Plant lives	1		20		1		19
Recoverable deferred taxes on AFUDC		Plant lives	—		18		—		17
Losses on reacquired debt		Term of related debt	—		2		—		2
Excess deferred taxes — TCJA	7	Various	—		—		23		—
Other		Various	1		14		1		8
Total regulatory assets			$	19	$	215	$	72	$	224

Regulatory Liabilities

Components of regulatory liabilities:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2020				Dec. 31, 2019
Regulatory Liabilities			Current		Noncurrent		Current		Noncurrent
Plant removal costs	1, 10	Various	$	—	$	184	$	—	$	171
Deferred income tax adjustments and TCJA refunds (a)	7	Various	—		161		51		196
Deferred electric production and natural gas costs		Less than one year	17		1		17		—
United States Department of Energy Settlement		Less than one year	12		—		10		—
Other		Various	2		4		1		4
Total regulatory liabilities			$	31	$	350	$	79	$	371

(a)    Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA.

^[1]

[1] Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA.

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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Debt Disclosure [Abstract]

Commercial Paper

Commercial paper outstanding for NSP-Wisconsin was as follows:

(Millions of Dollars, Except Interest Rates)	Three Months Ended Dec. 31, 2020			Year Ended
				2020			2019			2018
Borrowing limit	$	150		$	150		$	150		$	150
Amount outstanding at period end	19			19			65			51
Average amount outstanding	4			30			51			28
Maximum amount outstanding	24			95			93			103
Weighted average interest rate, computed on a daily basis	0.17		%	1.59		%	2.38		%	2.31		%
Weighted average interest rate at period end	0.17			0.17			1.97			2.89

Schedule of Debt To Total Capitalization Ratio

Debt-to-Total Capitalization Ratio (a)				Amount Facility May Be Increased (millions)	Additional Periods for Which a One-Year Extension May Be Requested (b)
2020		2019
46	%	48	%	N/A	1

Credit Facilities

^[1],[2]

(in millions):

Credit Facility (a)		Drawn (b)		Available
$	150	$	19	$	131

(a)This credit facility matures in June 2024.

(b)Includes outstanding commercial paper.

Schedule of Long-Term Debt

Long-term debt obligations for NSP-Wisconsin as of Dec. 31 (millions of dollars):

Financing Instrument	Interest Rate		Maturity Date	2020		2019
City of La Crosse resource recovery bond	6.00	%	Nov 1, 2021	$	19	$	19
First mortgage bonds	3.30		June 15, 2024	100		100
First mortgage bonds	3.30		June 15, 2024	100		100
First mortgage bonds	6.38		Sept. 1, 2038	200		200
First mortgage bonds	3.70		Oct. 1, 2042	100		100
First mortgage bonds	3.75		Dec. 1, 2047	100		100
First mortgage bonds	4.20		Sept. 1, 2048	200		200
First mortgage bonds (a)	3.05		May 1, 2051	100		—
Unamortized discount				(4)		(3)
Unamortized debt issuance cost				(9)		(8)
Current maturities				(19)		—
Total long-term debt				$	887	$	808

(a)2020 financing.

Schedule of Maturities of Long-term Debt

Maturities of long-term debt:

(Millions of Dollars)
2021	$	19
2022	—
2023	—
2024	200
2025	—

Dividend Payment Restrictions

Equity to Total Capitalization Ratio Required Range			Equity to Total Capitalization Ratio Actual
Low		High	2020
52.5	%	N/A	52.8	%

Unrestricted Retained Earnings			Total Capitalization		Limit on Total Capitalization (a)
$	7	million	1,940	million	N/A

(a) NSP-Wisconsin cannot pay annual dividends in excess of forecasted levels if its average equity-to-total capitalization ratio falls below the commission authorized level.

[1] Includes outstanding commercial paper

[2] This credit facility matures in June 2024.

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Revenues Revenues (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

NSP-Wisconsin’s operating revenues consisted of the following:

	Year Ended Dec. 31, 2020
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	258	$	64	$	322
C&I	411		49		460
Other	6		—		6
Total retail	675		113		788
Interchange	168		—		168
Other	—		4		4
Total revenue from contracts with customers	843		117		960
Alternative revenue and other	12		2		14
Total revenues	$	855	$	119	$	974

	Year Ended Dec. 31, 2019
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	240	$	73	$	313
C&I	409		57		466
Other	6		—		6
Total retail	655		130		785
Interchange	177		—		177
Other	1		4		5
Total revenue from contracts with customers	833		134		967
Alternative revenue and other	12		2		14
Total revenues	$	845	$	136	$	981

	Year Ended Dec. 31, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	255	$	73	$	—	$	328
C&I	444		62		—		506
Other	6		—		1		7
Total retail	705		135		1		841
Interchange	158		—		—		158
Other	4		5		—		9
Total revenue from contracts with customers	867		140		1		1,008
Alternative revenue and other	12		2		—		14
Total revenues	$	879	$	142	$	1	$	1,022

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Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Summary of Statute of Limitations Applicable to Open Tax Years [Table Text Block]

NSP-Wisconsin is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. Statute of limitations applicable to Xcel Energy’s consolidated federal income tax returns expire as follows:

Tax Year(s)	Expiration
2014 - 2016	July 2021

Reconciliation of Unrecognized Tax Benefits

Unrecognized tax benefits — permanent vs. temporary:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Unrecognized tax benefit — Permanent tax positions	$	1	$	2
Unrecognized tax benefit — Temporary tax positions	1		1
Total unrecognized tax benefit	$	2	$	3

Changes in unrecognized tax benefits:

(Millions of Dollars)	2020		2019		2018
Balance at Jan. 1	$	3	$	3	$	2
Additions for tax positions of prior years	1		—		1
Reductions for tax positions of prior years	(2)		—		—
Balance at Dec. 31	$	2	$	3	$	3

Tax Benefits Associated with NOL and Tax Credit Carryforwards

Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards:

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
NOL and tax credit carryforwards	$	(2)	$	(2)

NOL and Tax Credit Carryforwards

NOL amounts represent the tax loss that is carried forward and tax credits represent the deferred tax asset. NOL and tax credit carryforwards as of Dec. 31 were as follows:

(Millions of Dollars)	2020		2019
Federal tax credit carryforwards	$	7	$	5
State NOL carryforward	2		2

Schedule of Effective Income Tax Rate Reconciliation

Effective income tax rate for years ended Dec. 31:

	2020		2019 (a)		2018 (a)
Federal statutory rate	21.0	%	21.0	%	21.0	%
State income tax on pretax income, net of federal tax effect	6.2		6.2		6.2
Increases (decreases) in tax from:
Plant regulatory differences (b)	(19.3)		(5.2)		(1.5)
Amortization of excess nonplant deferred taxes	(12.6)		—		—
Other tax credits, net NOL & tax credit allowances	(1.5)		(1.8)		(0.8)
Change in unrecognized tax benefits	(0.8)		0.7		0.4
Reversal of prior regulatory differences	—		(3.6)		—
Other, net	—		(0.5)		(0.7)
Effective income tax rate	(7.0)	%	16.8	%	24.6	%

(a)Prior periods have been reclassified to conform to current year presentation.

(b)Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions.

Schedule of Components of Income Tax Expense (Benefit)

Components of income tax expense for years ended Dec. 31:

(Millions of Dollars)	2020		2019		2018
Current federal tax expense	$	25	$	6	$	8
Current state tax expense	6		5		2
Current change in unrecognized tax (benefit) expense	(1)		1		—
Deferred federal tax (benefit) expense	(37)		3		16
Deferred state tax expense	1		2		7
Deferred ITCs	(1)		(1)		(1)
Total income tax (benefit) expense	$	(7)	$	16	$	32

Components of deferred income tax expense as of Dec. 31:

(Millions of Dollars)	2020		2019		2018
Deferred tax expense excluding items below	$	9	$	17	$	24
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities	(45)		(12)		(1)
Deferred tax (benefit) expense	$	(36)	$	5	$	23

Schedule of Deferred Tax Assets and Liabilities

Components of net deferred tax liability as of Dec. 31:

(Millions of Dollars)	2020		2019 (a)
Deferred tax liabilities:
Difference between book and tax bases of property	$	324	$	304
Regulatory assets	32		50
Pension expense	12		14
Other	9		7
Total deferred tax liabilities	$	377	$	375
Deferred tax assets:
Regulatory liabilities	$	41	$	47
Tax credit carryforward	8		5
Environmental remediation	6		6
Other employee benefits	4		4
Rate refund	4		9
Deferred ITCs	3		3
Other	4		3
Total deferred tax assets	$	70	$	77
Net deferred tax liability	$	307	$	298

(a) Prior periods have been reclassified to conform to current year presentation.

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Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level

	Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	1	$	—	$	1	$	—	$	1

(a)NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2020. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)Included in prepayments and other current assets balance of $7 million at Dec. 31, 2020 on the consolidated balance sheets.

	Dec. 31, 2019
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	1	$	—	$	1	$	—	$	1

(a)NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2019. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)Included in prepayments and other current assets balance of $5 million at Dec. 31, 2019 on the consolidated balance sheets.

Carrying Amount and Fair Value of Long-term Debt

As of Dec. 31, other financial instruments for which the carrying amount did not equal fair value:

	2020				2019
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	906	$	1,124	$	808	$	924

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Benefit Plans and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2020

Benefit Plans and Other Postretirement Benefits [Abstract]

Funded Status of Plans

	Pension Benefits				Postretirement Benefits
(Millions of Dollars)	2020		2019		2020		2019
Change in Benefit Obligation:
Obligation at Jan. 1	$	144	$	140	$	13	$	13
Service cost	4		4		—		—
Interest cost	5		6		1		1
Actuarial loss	13		8		—		—
Benefit payments	(12)		(14)		(1)		(1)
Obligation at Dec. 31	$	154	$	144	$	13	$	13
Change in Fair Value of Plan Assets:
Fair value of plan assets at Jan. 1	$	124	$	110	$	—	$	—
Actual return on plan assets	21		21		—		—
Employer contributions	7		7		1		1
Benefit payments	(12)		(14)		(1)		(1)
Fair value of plan assets at Dec. 31	$	140	$	124	$	—	$	—
Funded status of plans at Dec. 31	$	(14)	$	(20)	$	(13)	$	(13)
Amounts recognized in the Consolidated Balance Sheet at Dec. 31:
Current liabilities	$	—	$	—	$	(1)	$	(1)
Noncurrent liabilities	(14)		(20)		(12)		(12)
Net amounts recognized	$	(14)	$	(20)	$	(13)	$	(13)

	Pension Benefits				Postretirement Benefits
Significant Assumptions Used to Measure Benefit Obligations:	2020		2019		2020		2019
Discount rate for year-end valuation	2.71	%	3.49	%	2.65	%	3.47	%
Expected average long-term increase in compensation level	3.75	%	3.75	%	N/A		N/A
Mortality table	Pri-2012		Pri-2012		Pri-2012		Pri-2012
Health care costs trend rate — initial: Pre-65	N/A		N/A		5.50	%	6.00	%
Health care costs trend rate — initial: Post-65	N/A		N/A		5.00	%	5.10	%
Ultimate trend assumption — initial: Pre-65	N/A		N/A		4.50	%	4.50	%
Ultimate trend assumption — initial: Post-65	N/A		N/A		4.50	%	4.50	%
Years until ultimate trend is reached	N/A		N/A		5		3

Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost

	Pension Benefits				Postretirement Benefits
(Millions of Dollars)	2020		2019		2020		2019
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost:
Net loss	$	60	$	64	$	7	$	7
Prior service credit	—		—		(1)		(1)
Total	$	60	$	64	$	6	$	6
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates:
Current regulatory assets	$	4	$	4	$	—	$	—
Noncurrent regulatory assets	56		60		6		6
Total	$	60	$	64	$	6	$	6

Components of Net Periodic Benefit Costs

	Pension Benefits									Postretirement Benefits
(Millions of Dollars)	2020			2019			2018			2020			2019			2018
Service cost	$	4		$	4		$	5		$	—		$	—		$	—
Interest cost	5			6			5			1			1			1
Expected return on plan assets	(8)			(8)			(9)			—			—			—
Amortization of net loss	5			4			6			—			—			—
Settlement charge (a)	—			—			7			—			—			—
Net periodic pension cost	$	6		$	6		$	14		$	1		$	1		$	1
Effects of regulation	7			—			(3)			—			—			—
Net benefit cost recognized for financial reporting	$	13		$	6		$	11		$	1		$	1		$	1
Significant Assumptions Used to Measure Costs:
Discount rate	3.49		%	4.31		%	3.63		%	3.47		%	4.32		%	3.62		%
Expected average long-term increase in compensation level	3.75			3.75			3.75			—			—			—
Expected average long-term rate of return on assets	7.10			7.10			7.10			4.50			4.50			5.30

(a)A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2018, as a result of lump-sum distributions during the 2018 plan year, NSP-Wisconsin recorded a total pension settlement charge of $7 million in 2018, a total of $2 million of that amount was recorded in the income statement in 2018. There were no settlement charges recorded to the qualified pension plans in 2020 and 2019.

Target Asset Allocations and Plan Assets Measured at Fair Value

Target asset allocations:

	Pension Benefits				Postretirement Benefits
	2020		2019		2020		2019
Domestic and international equity securities	35	%	37	%	15	%	15	%
Long-duration fixed income and interest rate swap securities	35		30		—		—
Short-to-intermediate fixed income securities	13		14		72		72
Alternative investments	15		17		9		9
Cash	2		2		4		4
Total	100	%	100	%	100	%	100	%

The asset allocations above reflect target allocations approved in the calendar year to take effect in the subsequent year

Projected Benefit Payments for the Pension and Postretirement Benefit Plans

(Millions of Dollars)	Projected Pension Benefit Payments		Gross Projected Postretirement Health Care Benefit Payments		Expected Medicare Part D Subsidies		Net Projected Postretirement Health Care Benefit Payments
2021	$	13	$	1	$	—	$	1
2022	12		1		—		1
2023	12		1		—		1
2024	12		1		—		1
2025	12		1		—		1
2026-2030	57		3		—		3

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Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Estimated Minimum Purchases Under Fuel Contracts

(Millions of Dollars)	Refuse-derived fuel/wood		Natural gas supply		Natural gas storage and transportation
2021	$	5	$	8	$	16
2022	1		—		14
2023	1		—		11
2024	1		—		9
2025	1		—		8
Thereafter	3		—		14
Total (a)	$	12	$	8	$	72

Low-income Housing Limited Partnerships

(Millions of Dollars)	Dec. 31, 2020		Dec. 31, 2019
Current assets	$	—	$	—
Property, plant and equipment, net	1		1
Other noncurrent assets	—		—
Total assets	$	1	$	1
Current liabilities	$	—	$	—
Mortgages and other long-term debt payable	1		1
Other noncurrent liabilities	—		—
Total liabilities	$	1	$	1

Asset Retirement Obligations

NSP-Wisconsin’s AROs were as follows:

	2020
(Millions of Dollars)	Jan. 1, 2020		Cash Flow Revisions (a)		Dec. 31, 2020 (b)
Electric
Distribution	$	5	$	—	$	5
Steam, hydro and other production	4		4		8
Natural gas
Distribution	9		—		9
Total liability (c)	$	18	$	4	$	22

(a)In 2020, AROs were revised for changes in timing and estimates of cash flows. Revisions in steam, hydro and other production AROs primarily related to changes in cost estimates for remediation of ash containment facilities.

(b)There were no ARO amounts incurred or settled in 2020.

(c)Included in other long-term liabilities balance in the consolidated balance sheet.

	2019
(Millions of Dollars)	Jan. 1, 2019		Accretion		Cash Flow Revisions		Dec. 31, 2019 (a)
Electric
Distribution	$	5	$	—	$	—	$	5
Steam, hydro and other production	4		—		—		4
Natural gas
Distribution	9		1		(1)		9
Total liability (b)	$	18	$	1	$	(1)	$	18

(a)There were no ARO amounts incurred or settled in 2019.

(b)Included in other long-term liabilities balance in the consolidated balance sheet.

Schedule of Long-term Contracts for Purchase of Electric Power

Estimated minimum purchases under these contracts as of Dec. 31, 2020:

(Millions of Dollars)	Refuse-derived fuel/wood		Natural gas supply		Natural gas storage and transportation
2021	$	5	$	8	$	16
2022	1		—		14
2023	1		—		11
2024	1		—		9
2025	1		—		8
Thereafter	3		—		14
Total (a)	$	12	$	8	$	72

(a)Excludes additional amounts allocated to NSP-Wisconsin through intercompany charges.

Guarantee Issued and Outstanding

Guarantee issued and outstanding for NSP-Wisconsin:

(Millions of Dollars)	Guarantor	Guarantee Amount		Current Exposure		Triggering Event
Guarantee of customer loans for the Farm Rewiring Program (a)	NSP-Wisconsin	$	1	$	—	(b)

(a)As of Dec. 31, 2020, no claims were outstanding against the guarantee.

(b)The debtor becomes the subject of bankruptcy or other insolvency proceedings.

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Other Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2020

Stockholders' Equity Note [Abstract]

Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax

	Gains and Losses on Cash Flow Hedges
(Millions of Dollars)	2020		2019
Accumulated other comprehensive loss at Jan. 1	$	—	$	—
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $—) (a)	—		—
Net current period other comprehensive income (loss)	—		—
Accumulated other comprehensive loss at Dec. 31	$	—	$	—

(a)Included in interest charges.

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Segments and Related Information (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Results from Operations by Reportable Segment

(Millions of Dollars)	2020		2019		2018
Regulated Electric
Operating revenues - external (a)	$	855	$	845	$	879
Intersegment revenue	1		—		—
Total revenues	$	856	$	845	$	879
Depreciation and amortization	108		109		98
Interest charges and financing costs	34		34		32
Income tax expense	12		13		28
Net income	98		68		85
Regulated Natural Gas
Total revenues	$	119	$	136	$	142
Depreciation and amortization	48		29		28
Interest charges and financing costs	4		4		3
Income tax (benefit) expense	(20)		2		5
Net income	7		10		13
All Other
Total revenues (a)	$	—	$	—	$	1
Income tax expense (benefit)	1		1		(1)
Net income	2		1		—
Consolidated Total
Total revenues (a)	$	975	$	981	$	1,022
Reconciling eliminations	(1)		—		—
Total operating revenues	$	974	$	981	$	1,022
Depreciation and amortization	156		138		126
Interest charges and financing costs	38		38		35
Income tax (benefit) expense	(7)		16		32
Net income	107		79		98

(a)    Operating revenues include $168 million, $177 million and $158 million of intercompany revenue for the years ended Dec. 31, 2020, 2019 and 2018, respectively. See Note 12 for further information.

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Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2020

Related Party Transactions [Abstract]

Related Party Transactions

Significant affiliate transactions among the companies and related parties including billings under the Interchange Agreement for the years ended Dec. 31:

(Millions of Dollars)	2020		2019		2018
Operating revenues:
Electric	$	168	$	177	$	158
Operating expenses:
Purchased power	379		394		411
Transmission expense	61		64		63
Natural gas purchased for resale	1		1		—
Other operating expenses — paid to Xcel Energy Services Inc.	92		87		87

Accounts receivable and payable with affiliates at Dec. 31 were:

	2020				2019
(Millions of Dollars)	Accounts Receivable		Accounts Payable		Accounts Receivable		Accounts Payable
NSP-Minnesota	$	—	$	6	$	—	$	8
PSCo	1		—		—		—
Other subsidiaries of Xcel Energy Inc.	9		9		—		11
	$	10	$	15	$	—	$	19

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Summarized Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Summarized Quarterly Financial Data (Unaudited)

	Quarter Ended
(Millions of Dollars)	March 31, 2020		June 30, 2020		Sept. 30, 2020		Dec. 31, 2020
Operating revenues	$	257	$	218	$	251	$	248
Operating income	41		23		46		31
Net income	34		12		40		21

	Quarter Ended
(Millions of Dollars)	March 31, 2019		June 30, 2019		Sept. 30, 2019		Dec. 31, 2019
Operating revenues	$	276	$	229	$	244	$	232
Operating income	42		22		48		19
Net income	24		9		29		17

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Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation expense expressed as a percentage of average depreciable property	3.60%	3.60%	3.50%
Operating revenues
Minimum annual tolerance band percentage for future rate recovery or refund of fuel costs	2.00%
Cash and Cash Equivalents [Abstract]
Maximum number of months of remaining maturity at time of purchase to consider investments in certain instruments as cash equivalents	three months
Accounts and Financing Receivable, after Allowance for Credit Loss, Current and Noncurrent [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ 8	$ 6
Alternative Revenue Programs [Abstract]
Maximum number of months following end of annual period in which revenues are earned to be included in incentive programs	24 months
Percentage of Average Annual Operating Revenues	1.20%
Number of Years Annual Operating Revenues are Averaged	3 years
Public Utilities, Inventory [Line Items]
Inventories	$ 15	16
Materials and supplies
Public Utilities, Inventory [Line Items]
Inventories	7	7
Fuel
Public Utilities, Inventory [Line Items]
Inventories	4	4
Natural gas
Public Utilities, Inventory [Line Items]
Inventories	$ 4	$ 5

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Property Plant and Equipment Property Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	$ 3,880	$ 3,674
Accumulated Depreciation	1,396	1,315
Property, Plant and Equipment, Net	2,484	2,359
Electric plant
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	3,197	3,025
Natural gas plant
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	391	365
Common and other property
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	221	201
CWIP
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	$ 71	$ 83

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Property Plant and Equipment Joint Ownership (Details) $ in Millions	Dec. 31, 2020 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 357
Accumulated Depreciation	35
CWIP	0
Jointly Owned Electricity Generation Plant [Member] | La Crosse, Wis. to Madison, Wis.
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	188
Accumulated Depreciation	12
CWIP	$ 0
Percent Owned	37.00%
Jointly Owned Electricity Generation Plant [Member] | CapX2020 Transmission
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 169
Accumulated Depreciation	23
CWIP	$ 0
Percent Owned	80.00%

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Regulatory Assets and Liabilities, Regulatory Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Regulatory Asset, Current	$ 19	$ 72
Regulatory Asset, Noncurrent	215	224
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	0	7
Environmental Remediation Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current	13	35
Regulatory Asset, Noncurrent	94	108
Pension and Retiree Medical Obligations
Regulatory Assets [Line Items]
Regulatory Asset, Current	4	12
Regulatory Asset, Noncurrent	67	70
State Commission Adjustments
Regulatory Assets [Line Items]
Regulatory Asset, Current	1	1
Regulatory Asset, Noncurrent	20	19
Recoverable Deferred Taxes on AFUDC Recorded in Plant
Regulatory Assets [Line Items]
Regulatory Asset, Current	0	0
Regulatory Asset, Noncurrent	18	17
Losses on Reacquired Debt
Regulatory Assets [Line Items]
Regulatory Asset, Current	0	0
Regulatory Asset, Noncurrent	2	2
Excess deferred taxes - TCJA
Regulatory Assets [Line Items]
Regulatory Asset, Current	0	23
Regulatory Asset, Noncurrent	0	0
Other
Regulatory Assets [Line Items]
Regulatory Asset, Current	1	1
Regulatory Asset, Noncurrent	$ 14	$ 8

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Regulatory Assets and Liabilities, Regulatory Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		$ 31	$ 79
Regulatory Liability, Noncurrent		350	371
Plant Removal Costs
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		0	0
Regulatory Liability, Noncurrent		184	171
Deferred Income Tax Adjustments and TCJA Refunds
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	[1]	0	51
Regulatory Liability, Noncurrent	[1]	161	196
Deferred Electric Production And Natural Gas Costs
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		17	17
Regulatory Liability, Noncurrent		1	0
United States Department of Energy Settlement
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		12	10
Regulatory Liability, Noncurrent		0	0
Other
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		2	1
Regulatory Liability, Noncurrent		$ 4	$ 4

[1] Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA.

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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Commercial Paper (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Amount outstanding at period end	$ 19	$ 19	$ 65
Commercial Paper [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	150	150	150	$ 150
Amount outstanding at period end	19	19	65	51
Average amount outstanding	4	30	51	28
Maximum amount outstanding	$ 24	$ 95	$ 93	$ 103
Line of Credit Facility, Interest Rate During Period	0.17%	1.59%	2.38%	2.31%
Weighted average interest rate at period end (percentage)	0.17%	0.17%	1.97%	2.89%

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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Letters of Credit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 19	$ 65
NSP Wisconsin [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Current Maturities	(19)	0
Letter of Credit
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 0	0
Letter of Credit
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Period	1 year
Credit Facilities
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 0	$ 0

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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Credit Facilities (Details) - Credit Facilities $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed	65.00%
Line Of Credit Facility Minimum Threshhold Percentage Of Subsidiary Assets To Consolidated Assets Required To Initiate Cross Default Provisions	15.00%
Line of Credit Facility, Minimum Amount of Indebtedness in Default to Initiate Cross Default Provisions	$ 75
Long-term Line of Credit	$ 0	$ 0
NSP Wisconsin [Member]
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)	46.00%	48.00%
Credit Facility	$ 150
Drawn	19
Available	$ 131
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval	1

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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Long-Term Borrowings and Other Financing Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Long-Term Borrowings and Other Financing Instruments
Unamortized discount	$ (4)	$ (3)
Unamortized debt expense	(9)	(8)
Long-term debt, noncurrent	887	808
2021	19
2022	0
2023	0
2024	200
2025	0
NSP Wisconsin [Member]
Long-Term Borrowings and Other Financing Instruments
Long-term Debt, Current Maturities	$ (19)	0
Series Due Nov. 1, 2021 [Member] | City of La Crosse Resource Recovery Bond
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Debt Instrument, Face Amount	$ 19	19
Series Due June 15, 2024 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	3.30%
Debt Instrument, Face Amount	$ 100	100
Series Due June 15, 2024 2 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	3.30%
Debt Instrument, Face Amount	$ 100	100
Series Due Sept. 1, 2038 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	6.38%
Debt Instrument, Face Amount	$ 200	200
Series Due Oct. 1, 2042 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	3.70%
Debt Instrument, Face Amount	$ 100	100
Series Due December 1, 2047 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	3.75%
Debt Instrument, Face Amount	$ 100	100
Series Due December 1, 2048 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	4.20%
Debt Instrument, Face Amount	$ 200	200
Series Due May 1, 2051 [Member] | First Mortgage Bonds | NSP Wisconsin [Member]
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	3.05%
Debt Instrument, Face Amount	$ 100	$ 0

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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Deferred Financing Costs (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred Financing Costs [Abstract]
Deferred Finance Costs, Noncurrent, Net	$ 9	$ 8

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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Dividend and Other Capital-Related Restrictions (Details) $ in Millions	Dec. 31, 2020 USD ($)
Dividend and Other Capital-Related Restrictions [Abstract]
Minimum calendar year average equity to total capitalization ratio authorized by state commission	52.50%
Equity to total capitalization ratio	52.80%
Unrestricted Retained Earnings Per State Regulatory Commissions Dividend Restrictions	$ 7

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Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 960	$ 967	$ 1,008
Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	788	785	841
Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	322	313	328
Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	460	466	506
Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	6	7
Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	168	177	158
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	5	9
Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	14	14	14
Regulated Electric | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	843	833	867
Regulated Electric | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	675	655	705
Regulated Electric | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	258	240	255
Regulated Electric | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	411	409	444
Regulated Electric | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	6	6
Regulated Electric | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	168	177	158
Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	1	4
Regulated Electric | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	12	12	12
Regulated Natural Gas | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	117	134	140
Regulated Natural Gas | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	113	130	135
Regulated Natural Gas | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	64	73	73
Regulated Natural Gas | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	49	57	62
Regulated Natural Gas | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Regulated Natural Gas | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	4	5
Regulated Natural Gas | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	2	2	2
All Other | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers			1
All Other | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers			1
All Other | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers			0
All Other | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers			0
All Other | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers			1
All Other | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers			0
All Other | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers			0
All Other | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other			0
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	974	981	1,022
Operating Segments | Regulated Electric
Disaggregation of Revenue [Line Items]
Total revenues	855	845	879
Operating Segments | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues	$ 119	$ 136	142
Operating Segments | All Other
Disaggregation of Revenue [Line Items]
Total revenues			$ 1

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Income Taxes (Details) - USD ($)		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019		Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
Tax Audits [Abstract]
Tax Credit Carryforward, Amount							$ 7,000,000		$ 5,000,000
Environmental Remediation							6,000,000		6,000,000	[1]
Net Deferred Tax Liability associated with the Unrecognized Tax Benefit Amounts and Related NOLs and Tax Credit Carryforwards							(1,000,000)		(1,000,000)
Deferred Tax Assets, Tax Deferred Expense							36,000,000		5,000,000			$ 23,000,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%	[1]	21.00%	[1]
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		6.20%	6.20%	[1]	6.20%	[1]
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent	[2]	(19.30%)	(5.20%)	[1]	(1.50%)	[1]
Amortization of excess nonplant deferred taxes		12.60%	0.00%	[1]
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(1.50%)	(1.80%)	[1]	(0.80%)	[1]
Effective Income Tax Rate Reconcilation, Change in unrecognized tax benefits, percent		(0.80%)	0.70%	[1]	0.40%	[1]
Reversal of prior regulatory differences		0.00%	3.60%	[1]	0.00%	[1]
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		0.00%	(0.50%)	[1]	(0.70%)	[1]
Effective Income Tax Rate Reconciliation, Percent		(7.00%)	16.80%	[1]	24.60%	[1]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local							2,000,000		2,000,000
Unrecognized Tax Benefits, Income Tax Penalties Expense		$ 0	$ 0		$ 0
Potential Federal Tax Adjustments		0
Income Tax Expense (Benefit)		(7,000,000)	16,000,000		32,000,000
Unrecognized Tax Benefits [Abstract]
Unrecognized Tax Benefits - Permanent tax positions							1,000,000		2,000,000
Unrecognized tax benefit — Temporary tax positions							1,000,000		1,000,000
Total unrecognized tax benefit		3,000,000	3,000,000		3,000,000		2,000,000	$ 3,000,000	3,000,000		$ 3,000,000	3,000,000	$ 2,000,000
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at Jan. 1		3,000,000	3,000,000
Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions		1,000,000	0		1,000,000
Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions		(2,000,000)	0		0
Balance at Dec. 31		$ 2,000,000	$ 3,000,000		$ 3,000,000
Tax Benefits Associated With NOL And Tax Credit Carryforwards [Abstract]
NOL and tax credit carryforwards							(2,000,000)		(2,000,000)
Net Deferred Tax Liability associated with the Unrecognized Tax Benefit Amounts and Related NOLs and Tax Credit Carryforwards							(1,000,000)		(1,000,000)
Decrease in Unrecognized Tax Benefits is Reasonably Possible							1,000,000
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%	[1]	21.00%	[1]
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		6.20%	6.20%	[1]	6.20%	[1]
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent	[2]	19.30%	5.20%	[1]	1.50%	[1]
Amortization of excess nonplant deferred taxes		12.60%	0.00%	[1]
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(1.50%)	(1.80%)	[1]	(0.80%)	[1]
Effective Income Tax Rate Reconciliation, Percent		(7.00%)	16.80%	[1]	24.60%	[1]
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income Tax Expense (Benefit)		$ (7,000,000)	$ 16,000,000		$ 32,000,000
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred tax expense (benefit) excluding selected items		9,000,000	17,000,000		24,000,000
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities		(45,000,000)	(12,000,000)		(1,000,000)
Deferred Income Tax Expense (Benefit)		$ (36,000,000)	$ 5,000,000		$ 23,000,000
Deferred Tax Assets, Gross [Abstract]
Deferred Tax Assets, Tax Deferred Expense							36,000,000		5,000,000			$ 23,000,000
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		0.00%	(0.50%)	[1]	(0.70%)	[1]
Effective Income Tax Rate Reconcilation, Change in unrecognized tax benefits, percent		(0.80%)	0.70%	[1]	0.40%	[1]
Reversal of prior regulatory differences		0.00%	3.60%	[1]	0.00%	[1]
Net Deferred Tax Liablility [Member]
Tax Audits [Abstract]
Tax Credit Carryforward, Amount							8,000,000		5,000,000	[1]
Differences between book and tax basis of property		$ 324,000,000	$ 304,000,000	[1]
Regulatory Assets							32,000,000		50,000,000	[1]
Deferred tax liability - Pension expense							12,000,000		14,000,000	[1]
Deferred Tax Assets, Tax Deferred Expense, Other							9,000,000		7,000,000	[1]
Deferred Tax Liabilities, Tax Deferred Income							377,000,000		375,000,000	[1]
Regulatory Liabilities							41,000,000		47,000,000	[1]
other employee benefits							4,000,000		4,000,000	[1]
Deferred Tax Assets Rate Refund							4,000,000		9,000,000	[1]
Deferred ITCs		3,000,000	3,000,000	[1]
Deferred Tax Assets, Other							4,000,000		3,000,000	[1]
Deferred Tax Assets, Tax Deferred Expense							70,000,000		77,000,000	[1]
Deferred Tax Liabilities, Net							307,000,000		298,000,000	[1]
Deferred Tax Assets, Gross [Abstract]
Deferred Tax Assets Rate Refund							4,000,000		9,000,000	[1]
Deferred Tax Assets, Other							4,000,000		3,000,000	[1]
Deferred Tax Liabilities, Net							307,000,000		298,000,000	[1]
Regulatory Assets							32,000,000		50,000,000	[1]
Deferred tax liability - Pension expense							12,000,000		14,000,000	[1]
Deferred Tax Assets, Tax Deferred Expense, Other							9,000,000		7,000,000	[1]
Deferred Tax Liabilities, Tax Deferred Income							377,000,000		375,000,000	[1]
Differences between book and tax basis of property		324,000,000	304,000,000	[1]
Regulatory Liabilities							41,000,000		47,000,000	[1]
other employee benefits							4,000,000		4,000,000	[1]
Deferred ITCs		3,000,000	3,000,000	[1]
Deferred Tax Assets, Tax Deferred Expense							$ 70,000,000		$ 77,000,000	[1]
WISCONSIN
Tax Audits [Abstract]
Potential Tax Adjustments		0
income tax expense [Member]
Tax Audits [Abstract]
Deferred ITCs		1,000,000	1,000,000		$ 1,000,000
Current Federal Tax Expense (Benefit)		25,000,000	6,000,000		8,000,000
Current State and Local Tax Expense (Benefit)		6,000,000	5,000,000		2,000,000
Current Change In Unrecognized Tax Expense (Benefit)		(1,000,000)	1,000,000		0
Deferred Federal Income Tax Expense (Benefit)		(37,000,000)	3,000,000		16,000,000
Deferred State and Local Income Tax Expense (Benefit)		1,000,000	2,000,000		7,000,000
Income Tax Expense (Benefit)		(7,000,000)	16,000,000		32,000,000
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)		25,000,000	6,000,000		8,000,000
Current State and Local Tax Expense (Benefit)		6,000,000	5,000,000		2,000,000
Current Change In Unrecognized Tax Expense (Benefit)		(1,000,000)	1,000,000		0
Deferred Federal Income Tax Expense (Benefit)		(37,000,000)	3,000,000		16,000,000
Deferred State and Local Income Tax Expense (Benefit)		1,000,000	2,000,000		7,000,000
Income Tax Expense (Benefit)		(7,000,000)	16,000,000		32,000,000
Deferred Tax Assets, Gross [Abstract]
Deferred ITCs		$ 1,000,000	$ 1,000,000		$ 1,000,000

[1] Prior periods have been reclassified to conform to current year presentation.

[2] Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions.

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Interest Rate Derivatives (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Interest Rate Swap
Interest Rate Derivatives [Abstract]
Amount of accumulated other comprehensive gains (losses) related to interest rate derivatives expected to be reclassified into earnings within the next twelve months	$ 0	$ 0

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Impact of Derivative Activities on Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Fair Value Hedges, Net	$ 0	$ 0	$ 0
Not Designated as Hedging Instrument | Natural Gas Commodity Contract
Derivative [Line Items]
Derivative Instruments Gain (Loss) Reclassified To Regulatory Assets And Liabilities Net	1	1
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)	$ 1	$ 1

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Recurring Fair Value Measurement (Details) - USD ($) $ in Millions	Dec. 31, 2020		Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Prepayments and other	$ 7		$ 5
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	1		1
Netting	0	[1]	0	[2]
Derivative Asset, Net	1	[3]	1	[4]
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	1		1
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	$ 0		$ 0

[1] NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2020. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

[2] NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2019. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

[3] Included in prepayments and other current assets balance of $7 million at Dec. 31, 2020 on the consolidated balance sheets.

[4] Included in prepayments and other current assets balance of $5 million at Dec. 31, 2019 on the consolidated balance sheets.

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Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Long-term debt, Fair Value		$ 924
Long-term Debt, Gross	$ 906	$ 808
Level 2
Derivatives, Fair Value [Line Items]
Long-term debt, Fair Value	$ 1,124

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Fair Value of Financial Assets and Liabilities Fair Value Phantom (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Hedges, Net	$ 0	$ 0	$ 0

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Benefit Plans and Other Postretirement Benefits, Pension Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Operating and maintenance expenses		$ 191,000,000	$ 201,000,000	$ 203,000,000
Target Pension Asset Allocations [Abstract]
annual interest crediting rates [Domain]		1.78	2.74	3.57
annual interest crediting rates [Domain]		1.78	2.74	3.57
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan
Pension Benefits [Abstract]
Total benefit obligation		1,000,000	1,000,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Operating and maintenance expenses			2,000,000
Pension Benefits [Abstract]
Total benefit obligation		154,000,000	144,000,000	140,000,000
Net benefit cost recognized for financial reporting		$ 13,000,000	$ 6,000,000	$ 11,000,000
Minimum number of years historical achieved weighted average annual returns are used to determine investment return assumptions (in years)		20 years
Expected average long-term rate of return on assets (as a percent)		7.10%	7.10%	7.10%
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		100.00%	100.00%
Pension Plan [Member] | Domestic and international equity securities
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		35.00%	37.00%
Pension Plan [Member] | Long-duration fixed income and interest rate swap securities
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		35.00%	30.00%
Pension Plan [Member] | Short-to-intermediate fixed income securities
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		13.00%	14.00%
Pension Plan [Member] | Alternative investments
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		15.00%	17.00%
Pension Plan [Member] | Cash
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2.00%	2.00%
Forecast [Member] | Pension Plan [Member]
Pension Benefits [Abstract]
Expected average long-term rate of return on assets for next fiscal year (as a percent)	6.60%
Parent Company [Member] | Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan
Pension Benefits [Abstract]
Total benefit obligation		$ 43,000,000	$ 39,000,000
Net benefit cost recognized for financial reporting		$ 6,000,000	$ 4,000,000

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Benefit Plans and Other Postretirement Benefits, Fair Value of Pension Plan Assets (Details) - Pension Plan [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		$ 140	$ 124	$ 110
Plan assets at net asset value		44	41
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	[1]	0	0	$ (7)
NSP Wisconsin [Member]
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets			124
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement			(7)
Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		70	59
Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		26	24
Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Debt Securities [Member]
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		26	24
Plan assets at net asset value		0	0
Debt Securities [Member] | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Debt Securities [Member] | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		26	24
Debt Securities [Member] | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Domestic and international equity securities
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		4	3
Plan assets at net asset value		0	0
Domestic and international equity securities | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		4	3
Domestic and international equity securities | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Domestic and international equity securities | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Cash equivalents
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		8	6
Plan assets at net asset value		0	0
Cash equivalents | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		8	6
Cash equivalents | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Cash equivalents | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Other
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		1	(5)
Plan assets at net asset value		0	0
Other | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		1	(5)
Other | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Other | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Commingled funds
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		101	96
Plan assets at net asset value		44	41
Commingled funds | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		57	55
Commingled funds | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		0	0
Commingled funds | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		$ 0	$ 0

[1] A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2018, as a result of lump-sum distributions during the 2018 plan year, NSP-Wisconsin recorded a total pension settlement charge of $7 million in 2018, a total of $2 million of that amount was recorded in the income statement in 2018. There were no settlement charges recorded to the qualified pension plans in 2020 and 2019.

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Benefit Plans and Other Postretirement Benefits, Pension Plan Benefit Obligations, Cash Flows and Benefit Costs (Details) $ in Millions		1 Months Ended	12 Months Ended
		Jan. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) Plan	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Settlement Charge Recognized in Operating and Maintenance Expenses			$ 191	$ 201	$ 203
Significant Assumptions Used to Measure Costs [Abstract]
Liability, Defined Benefit Plan, Noncurrent			(28)	(33)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation at Dec. 31			141	132
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		$ 154	144	140
Service cost			4	4	5
Interest cost			5	6	5
Actuarial loss			13	8
Benefit payments			(12)	(14)
Obligation at Dec. 31			154	144	140
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		140	124	110
Actual return (loss) on plan assets			21	21
Employer contributions			7	7
Benefit payments			(12)	(14)
Fair value of plan assets at Dec. 31			140	124	110
Funded Status of Plans at Dec. 31 [Abstract]
Funded status			(14)	(20)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss			60	64
Prior service (credit) cost			0	0
Total			60	64
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets			4	4
Noncurrent regulatory assets			56	60
Total			$ 60	$ 64
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)			2.71%	3.49%
Expected average long-term increase in compensation level (as a percent)			3.75%	3.75%
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			$ 4	$ 4	5
Interest cost			5	6	5
Expected return on plan assets			(8)	(8)	(9)
Amortization of net loss			5	4	6
Settlement charge	[1]		0	0	7
Net periodic benefit cost			6	6	14
Net benefit cost recognized for financial reporting			$ 13	6	$ 11
Settlement Charge Recognized in Operating and Maintenance Expenses				$ 2
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)			3.49%	4.31%	3.63%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase			3.75%	3.75%	3.75%
Liability, Defined Benefit Plan, Current			$ 0	$ 0
Liability, Defined Benefit Plan, Noncurrent			(14)	(20)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position			(14)	(20)
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation			$ 7	$ 0	$ 3
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets			7.10%	7.10%	7.10%
Pension Plan [Member] | NSP Wisconsin [Member]
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1			$ 124
Fair value of plan assets at Dec. 31				$ 124
Cash Flows [Abstract]
Payment for Pension Benefits			$ 7	7	$ 10
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charge				7
Significant Assumptions Used to Measure Costs [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets			7.10%
Other Postretirement Benefits Plan [Member]
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		13	$ 13	13
Service cost			0	0	0
Interest cost			1	1	1
Actuarial loss			0	0
Benefit payments			(1)	(1)
Obligation at Dec. 31			13	13	13
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		0	0	0
Actual return (loss) on plan assets			0	0
Employer contributions			1	1
Benefit payments			(1)	(1)
Fair value of plan assets at Dec. 31			0	0	0
Funded Status of Plans at Dec. 31 [Abstract]
Funded status			(13)	(13)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss			7	7
Prior service (credit) cost			(1)	(1)
Total			6	6
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets			0	0
Noncurrent regulatory assets			6	6
Total			$ 6	$ 6
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)			2.65%	3.47%
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			$ 0	$ 0	0
Interest cost			1	1	1
Expected return on plan assets			0	0	0
Amortization of net loss			0	0	0
Settlement charge	[1]		0	0	0
Net periodic benefit cost			1	1	1
Net benefit cost recognized for financial reporting			$ 1	$ 1	$ 1
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)			3.47%	4.32%	3.62%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase			0.00%	0.00%	0.00%
Liability, Defined Benefit Plan, Current			$ 1	$ 1
Liability, Defined Benefit Plan, Noncurrent			(12)	(12)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position			$ (13)	$ (13)
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65			5.50%	6.00%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65			5.00%	5.10%
Ultimate health care trend assumption rate (as a percent)			4.50%	4.50%
Period until ultimate trend rate is reached (in years)			5	3
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation			$ 0	$ 0	$ 0
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets			4.50%	4.50%	5.30%
Subsequent Event | Pension Plan [Member]
Cash Flows [Abstract]
Payment for Pension Benefits		125
Subsequent Event | Pension Plan [Member] | NSP Wisconsin [Member]
Cash Flows [Abstract]
Payment for Pension Benefits		$ 5
Parent Company [Member] | Pension Plan [Member]
Cash Flows [Abstract]
Number of pension plans to which contributions were made | Plan			4

[1] A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2018, as a result of lump-sum distributions during the 2018 plan year, NSP-Wisconsin recorded a total pension settlement charge of $7 million in 2018, a total of $2 million of that amount was recorded in the income statement in 2018. There were no settlement charges recorded to the qualified pension plans in 2020 and 2019.

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Benefit Plans and Other Postretirement Benefits, Defined Contribution Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Administrative Expense	$ 2	$ 2	$ 2
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for year-end valuation (as a percent)	2.65%	3.47%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65	5.50%	6.00%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65	5.00%	5.10%
Ultimate health care trend assumption rate (as a percent)	4.50%	4.50%
Period until ultimate trend rate is reached (in years)	5	3
Net benefit cost recognized for financial reporting	$ 1	$ 1	1
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for year-end valuation (as a percent)	2.71%	3.49%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.75%	3.75%
Net benefit cost recognized for financial reporting	$ 13	$ 6	$ 11
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan | Parent Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Net benefit cost recognized for financial reporting	$ 6	$ 4

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Benefit Plans and Other Postretirement Benefits, Postretirement Health Care Benefits (Details) - Other Postretirement Benefits Plan [Member]	Dec. 31, 2020	Dec. 31, 2019
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%	100.00%
Domestic and international equity securities
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15.00%	15.00%
Short-to-intermediate fixed income securities
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	72.00%	72.00%
Alternative investments
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	9.00%	9.00%
Cash
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4.00%	4.00%

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Benefit Plans and Other Postretirement Benefits, Fair Value of Postretirement Benefit Plan Assets (Details) - Other Postretirement Benefits Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%	100.00%
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	$ 0	$ 0	$ 0	$ 0
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	$ 0	$ 0	$ 0
Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4.00%	4.00%
Domestic and international equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15.00%	15.00%
Long-duration fixed income and interest rate swap securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%	0.00%
Short-to-intermediate fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	72.00%	72.00%
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	9.00%	9.00%

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Benefit Plans and Other Postretirement Benefits, Postretirement Benefit Plan Benefit Obligations, Cash Flows and Benefit Costs (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Funded Status of Plans at Dec. 31 [Abstract]
Noncurrent liabilities			$ (28)	$ (33)
Pension Plan [Member]
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		$ 154	144	140
Service cost			4	4	$ 5
Interest cost			5	6	5
Actuarial loss			13	8
Benefit payments			(12)	(14)
Obligation at Dec. 31			154	144	140
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		140	124	110
Actual return (loss) on plan assets			21	21
Employer contributions			7	7
Benefit payments			(12)	(14)
Fair value of plan assets at Dec. 31			140	124	110
Funded Status of Plans at Dec. 31 [Abstract]
Funded status			(14)	(20)
Current liabilities			0	0
Noncurrent liabilities			(14)	(20)
Net postretirement amounts recognized on consolidated balance sheets			(14)	(20)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss			60	64
Prior service (credit) cost			0	0
Total			60	64
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets			4	4
Noncurrent regulatory assets			56	60
Total			$ 60	$ 64
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)			2.71%	3.49%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase			3.75%	3.75%
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			$ 4	$ 4	5
Interest cost			5	6	5
Expected return on plan assets			(8)	(8)	(9)
Amortization of net loss			5	4	6
Settlement charge	[1]		0	0	7
Net periodic benefit cost			$ 6	$ 6	$ 14
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)			3.49%	4.31%	3.63%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase			3.75%	3.75%	3.75%
Expected average long-term rate of return on assets (as a percent)			7.10%	7.10%	7.10%
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation			$ (7)	$ 0	$ (3)
Net benefit cost recognized for financial reporting			13	6	11
Other Postretirement Benefits Plan [Member]
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		13	13	13
Service cost			0	0	0
Interest cost			1	1	1
Actuarial loss			0	0
Benefit payments			(1)	(1)
Obligation at Dec. 31			13	13	13
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		0	0	0
Actual return (loss) on plan assets			0	0
Employer contributions			1	1
Benefit payments			(1)	(1)
Fair value of plan assets at Dec. 31			0	0	0
Funded Status of Plans at Dec. 31 [Abstract]
Funded status			(13)	(13)
Current liabilities			(1)	(1)
Noncurrent liabilities			(12)	(12)
Net postretirement amounts recognized on consolidated balance sheets			(13)	(13)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss			7	7
Prior service (credit) cost			(1)	(1)
Total			6	6
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets			0	0
Noncurrent regulatory assets			6	6
Total			$ 6	$ 6
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)			2.65%	3.47%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65			5.50%	6.00%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65			5.00%	5.10%
Ultimate health care trend assumption rate (as a percent)			4.50%	4.50%
Period until ultimate trend rate is reached (in years)			5	3
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			$ 0	$ 0	0
Interest cost			1	1	1
Expected return on plan assets			0	0	0
Amortization of net loss			0	0	0
Settlement charge	[1]		0	0	0
Net periodic benefit cost			$ 1	$ 1	$ 1
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)			3.47%	4.32%	3.62%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase			0.00%	0.00%	0.00%
Expected average long-term rate of return on assets (as a percent)			4.50%	4.50%	5.30%
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation			$ 0	$ 0	$ 0
Net benefit cost recognized for financial reporting			$ 1	$ 1	$ 1
Subsequent Event | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits		$ 125

[1] A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2018, as a result of lump-sum distributions during the 2018 plan year, NSP-Wisconsin recorded a total pension settlement charge of $7 million in 2018, a total of $2 million of that amount was recorded in the income statement in 2018. There were no settlement charges recorded to the qualified pension plans in 2020 and 2019.

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Benefit Plans and Other Postretirement Benefits, Projected Benefit Payments (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Defined Contribution Plan, Administrative Expense		$ 2	$ 2	$ 2
Pension Plan [Member]
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2021		13
2022		12
2023		12
2024		12
2025		12
2026-2030		57
Pension Plan [Member] | NSP Wisconsin [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits		7	7	10
Pension Plan [Member] | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits		150	154	150
Pension Plan [Member] | Subsequent Event
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits	$ 125
Pension Plan [Member] | Subsequent Event | NSP Wisconsin [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits	5
Pension Plan [Member] | Subsequent Event | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2021		1
2022		1
2023		1
2024		1
2025		1
2026-2030		3
Expected Medicare Part D Subsidies [Abstract]
2021		0
2022		0
2023		0
2024		0
2025		0
2026-2030		0
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
2021		1
2022		1
2023		1
2024		1
2025		1
2026-2030		3
Defined Benefit Plan, Overfunded Plan [Member] | NSP Wisconsin [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits		1	1
Defined Benefit Plan, Overfunded Plan [Member] | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits		$ 11	$ 15	$ 11
Defined Benefit Plan, Overfunded Plan [Member] | Subsequent Event | NSP Wisconsin [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits	1
Defined Benefit Plan, Overfunded Plan [Member] | Subsequent Event | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits	$ 10

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Commitments and Contingencies Gas Trading Litigation (Details)	Dec. 31, 2020
Gas Trading Litigation
Public Utilities, General Disclosures [Line Items]
Loss Contingency, Pending Claims, Number	2
Breckenridge Litigation [Domain]
Public Utilities, General Disclosures [Line Items]
Loss Contingency, Pending Claims, Number	3,000,000

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Commitments and Contingencies MISO ROE Complaints (Details) - Federal Energy Regulatory Commission (FERC) [Member] - NSP Minnesota and NSP Wisconsin [Member] [Member] - FERC Proceeding, MISO ROE Complaint [Member]	1 Months Ended		7 Months Ended	8 Months Ended	9 Months Ended	14 Months Ended
	Feb. 28, 2015	Nov. 30, 2013	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2017	Dec. 31, 2020
Public Utilities, General Disclosures [Line Items]
Public Utilities, Base Return On Equity Charged To Customers Through Transmission Formula Rates	12.38%	12.38%
Public Utilities, ROE Applicable To Transmission Formula Rates In The MISO Region, Recommended By Third Parties	8.67%	9.15%
Public Utilities, ROE Applicable To Transmission Formula Rates In The MISO Region, Approved					10.32%
Public Utilities, ROE developed with new approach						9.88%
Public Utilities, ROE New Base, Complaint Number 1				10.02%
Basis Point Reduction			1000.00%
Basis Point Reduction - First Complaint			200000000.00%
Basis Point Reduction - Second Complaint			100000000.00%

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Commitments and Contingencies MGP Sites (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Ashland MGP Site [Member]
Loss Contingencies [Line Items]
Current Cost Estimate for Site Remediation	$ 199
Accrual for Environmental Loss Contingencies, Gross	$ 19	$ 23
Carrying cost percentage to be applied to unamortized regulatory asset	3.00%
Other MGP, Landfill, or Disposal Sites [Domain]
Loss Contingencies [Line Items]
Number of identified MGP, landfill, or disposal sites under current investigation and/or remediation	1

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Commitments and Contingencies Environmental Requirements - Water and Waste (Details) - Federal Clean Water Act Section 316 (b) [Member] $ in Millions	Dec. 31, 2020 USD ($)
Loss Contingencies [Line Items]
Minimum number of plants which could be required to make improvements to reduce entrainment	2
Capital Addition Purchase Commitments [Member]
Loss Contingencies [Line Items]
Liability for estimated cost to comply with regulation	$ 4
Liability for estimated cost to comply with impingement and entrainment regulation	$ 4

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Commitments and Contingencies, Asset Retirement Obligations (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	[1]	$ 18	[2],[3]	$ 18
Accretion	[1]			1
Cash Flow Revisions		4	[2],[4]	(1)	[1]
Ending balance	[2]	22	[5]	18	[1],[3]
Electric Plant Electric Distribution
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		5	[3]	5
Accretion				0
Cash Flow Revisions		0	[4]	0
Ending balance		5	[5]	5	[3]
Electric Plant Steam Production Asbestos
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		4	[3]	4
Accretion				0
Cash Flow Revisions		4	[4]	0
Ending balance		8	[5]	4	[3]
Natural Gas Plant Gas Distribution
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		9	[3]	9
Accretion				1
Cash Flow Revisions		0	[4]	(1)
Ending balance		$ 9	[5]	$ 9	[3]

[1] Included in other long-term liabilities balance in the consolidated balance sheet

[2] Included in other long-term liabilities balance in the consolidated balance sheet.

[3] There were no ARO amounts incurred or settled in 2019.

[4] In 2020, AROs were revised for changes in timing and estimates of cash flows. Revisions in steam, hydro and other production AROs primarily related to changes in cost estimates for remediation of ash containment facilities.

[5] There were no ARO amounts incurred or settled in 2020.

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Commitments and Contingencies, Joint Operating System (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) Reactor Plant Counterparty
Joint Operating System [Abstract]
Number of companies covered by FERC approved Interchange Agreement | Counterparty	2
NSP-Minnesota | Nuclear Insurance
Joint Operating System [Abstract]
Nuclear insurance coverage secured for the Company's public liability exposure	$ 450
Nuclear insurance coverage exposure funded by the Secondary Financial Protection Program	13,300
Maximum assessments per reactor per accident	$ 138
Number of owned and licensed reactors | Reactor	3
Maximum funding requirement per reactor for any one year	$ 21
Number of nuclear plant sites operated by NSP-Minnesota | Plant	2
Maximum assessments for business interruption insurance each calendar year	$ 11
Maximum assessment for property damage insurance NSP-Minnesota is subject to each calendar year	34
NSP-Minnesota | Maximum | Nuclear Insurance
Joint Operating System [Abstract]
Maximum possible loss contingency	13,800
Insurance coverage limits for NSP-Minnesota's nuclear plant sites	2,800
Business Interruption Insurance Coverage Provided by NEIL	$ 350

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Commitments and Contingencies, Fuel Contracts (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Minimum annual tolerance band percentage for future rate recovery or refund of fuel costs	2.00%
Coal
Fuel Contracts [Abstract]
2021	$ 5
2022	1
2023	1
2024	1
2025	1
Thereafter	3
Total	12	[1]
Natural Gas Supply
Fuel Contracts [Abstract]
2021	8
2022	0
2023	0
2024	0
2025	0
Thereafter	0
Total	8	[1]
Natural Gas Storage and Transportation
Fuel Contracts [Abstract]
2021	16
2022	14
2023	11
2024	9
2025	8
Thereafter	14
Total	$ 72	[1]

[1] Excludes additional amounts allocated to NSP-Wisconsin through intercompany charges.

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Commitments and Contingencies, Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Amount Reflected in Consolidated Balance Sheets [Abstract]
Current assets	$ 0	$ 0
Property, plant and equipment, net	1	1
Other noncurrent assets	0	0
Variable interest entity, consolidated, carrying amount, assets	1	1
Current liabilities	0	0
Mortgages and other long-term debt payable	1	1
Other noncurrent liabilities	0	0
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 1	$ 1

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Commitments and Contingencies, Guarantees (Details)	Dec. 31, 2020 USD ($)
Guarantee [Abstract]
Guarantees issued and outstanding	$ 0
Current exposure under these guarantees	0	[1]
Payment or Performance Guarantee | Customer Loans for Farm Rewiring Program
Guarantee [Abstract]
Guarantees issued and outstanding	$ 1,000,000	[1]

[1] As of Dec. 31, 2020, no claims were outstanding against the guarantee.

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Other Comprehensive Income (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	$ 967.0
Accumulated other comprehensive loss at end of period	1,068.0
Gains and Losses on Cash Flow Hedges | Interest Rate Swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of losses, Derivatives	$ 0.0	[1]

[1] Included in interest charges.

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Other Comprehensive Income Other Comprehensive Income Phantom (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense (Benefit)	$ (7)	$ 16	$ 32

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Segments and Related Information (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Unregulated Operating Revenue										$ 0	$ 0	$ 1
Regulated and Unregulated Operating Revenue		$ 248	$ 251	$ 218	$ 257	$ 232	$ 244	$ 229	$ 276	974	981	1,022
Depreciation and amortization										156	138	126
Interest charges and financing costs										38	38	35
Income Tax Expense (Benefit)										(7)	16	32
Net income		$ 21	$ 40	$ 12	$ 34	$ 17	$ 29	$ 9	$ 24	107	79	98
Regulated Operating Revenue, Electric, Affiliate										168	177	158
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues										856	845	879
Depreciation and amortization										108	109	98
Interest charges and financing costs										34	34	32
Income Tax Expense (Benefit)										12	13	28
Net income										98	68	85
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues										119	136	142
Depreciation and amortization										48	29	28
Interest charges and financing costs										4	4	3
Income Tax Expense (Benefit)										(20)	2	5
Net income										7	10	13
All Other
Segment Reporting Information [Line Items]
Income Tax Expense (Benefit)										1	1	(1)
Net income										2	1	0
Operating Segments
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]									975	981	1,022
Operating Segments | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric	[1]									855	845	879
Operating Segments | All Other
Segment Reporting Information [Line Items]
Unregulated Operating Revenue	[1]									0	0	1
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue										(1)	0	0
Intersegment Eliminations | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric										$ 1	$ 0	$ 0

[1] (a)    Operating revenues include $168 million, $177 million and $158 million of intercompany revenue for the years ended Dec. 31, 2020, 2019 and 2018, respectively. See Note 12 for further information.

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Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	$ 10	$ 0
Accounts payable	15	19
NSP-Minnesota
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	0	0
Accounts payable	6	8
PSCo
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	1	0
Accounts payable	0	0
Other subsidiaries of Xcel Energy Inc.
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	9	0
Accounts payable	9	11
Purchased Power
Operating expenses
Costs and Expenses, Related Party	379	394	$ 411
Transmission Expense
Operating expenses
Costs and Expenses, Related Party	61	64	63
Natural Gas Purchase for Resale
Operating expenses
Costs and Expenses, Related Party	1	1	0
Other Expense
Operating expenses
Costs and Expenses, Related Party	92	87	87
Electricity, US Regulated
Operating revenues
Revenue from Related Parties	$ 168	$ 177	$ 158

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Summarized Quarterly Financial Data (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Regulated and Unregulated Operating Revenue	$ 248	$ 251	$ 218	$ 257	$ 232	$ 244	$ 229	$ 276	$ 974	$ 981	$ 1,022
Operating income	31	46	23	41	19	48	22	42	141	131	159
Net income	$ 21	$ 40	$ 12	$ 34	$ 17	$ 29	$ 9	$ 24	$ 107	$ 79	$ 98

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Schedule II, Valuation and Qualifying Accounts (Details) - Allowance for Bad Debts - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Jan. 1		$ 6	$ 6	$ 5
Charged to costs and expenses		7	7	4
Charged to other accounts	[1]	1	2	1
Deductions from reserves	[2]	(6)	(9)	(4)
Balance at Dec. 31		$ 8	$ 6	$ 6

[1] Recovery of amounts previously written-off.

[2] Deductions related primarily to bad debt write-offs.