Regulatory Assets and Liabilities

12 Months Ended

Dec. 31, 2024

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, 2024				Dec. 31, 2023
Regulatory Assets			Current		Noncurrent		Current		Noncurrent
Pension and retiree medical obligations	9	Various	$	2	$	60	$	2	$	62
Environmental remediation costs	1, 10	Various	13		34		13		48
Recoverable deferred taxes on AFUDC		Plant lives	—		31		—		26
State commission adjustments		Plant lives	1		21		1		22
Net AROs (a)	1, 10	Various	—		21		—		21
Other		Various	7		1		8		6
Total regulatory assets			$	23	$	168	$	24	$	185

(a)Includes amounts recorded for future recovery of AROs and NSP-Wisconsin’s share of nuclear decommissioning accruals.

Components of regulatory liabilities:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2024				Dec. 31, 2023
Regulatory Liabilities			Current		Noncurrent		Current		Noncurrent
Plant removal costs	1, 10	Various	$	—	$	276	$	—	$	251
Deferred income tax adjustments and TCJA refunds (a)	7	Various	—		134		—		140
IRA deferral		One to three years	3		37		—		—
DOE Settlement		One to two years	4		4		4		6
Deferred natural gas and electric energy/fuel costs		Less than one year	13		—		28		—
Other		Various	9		5		10		10
Total regulatory liabilities			$	29	$	456	$	42	$	407

(a)Includes the revaluation of recoverable/regulated plant accumulated deferred income taxes and revaluation impact of non-plant accumulated deferred income taxes due to the TCJA.

NSP-Wisconsin’s regulatory assets not earning a return include the unfunded portion of pension and retiree medical obligations and net AROs (i.e. deferrals for which cash has not been disbursed). At Dec. 31, 2024 and 2023, there were no regulatory assets of past expenditures that were not eligible to earn a return.