Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Summary of Income Tax Expense

The following table is a summary of income tax expense for the years ended December 31:

(in millions)	2024		2023		2022
Current tax expense (benefit)	$	(307.0)	$	(14.8)	$	50.2
Deferred income taxes, net	538.7		229.9		278.5
ITCs	(9.7)		(10.5)		(5.8)
Total income tax expense	$	222.0	$	204.6	$	322.9

Statutory rate reconciliation

The provision for income taxes for each of the years ended December 31 differs from the amount of income tax determined by applying the applicable United States statutory federal income tax rate to income before income taxes as a result of the following:

	2024				2023				2022
(in millions)	Amount		Effective Tax Rate		Amount		Effective Tax Rate		Amount		Effective Tax Rate
Statutory federal income tax	$	367.3	21.0	%	$	322.6	21.0	%	$	363.5	21.0	%
State income taxes net of federal tax benefit	108.0		6.2	%	94.3		6.1	%	109.7		6.3	%
PTCs, net	(200.1)		(11.5)	%	(168.2)		(10.9)	%	(107.6)		(6.2)	%
Federal excess deferred tax amortization (1)	(36.7)		(2.1)	%	(37.6)		(2.4)	%	(36.9)		(2.1)	%
AFUDC-Equity	(12.6)		(0.7)	%	(12.4)		(0.8)	%	(6.2)		(0.4)	%
Other, net	(3.9)		(0.2)	%	5.9		0.3	%	0.4		—	%
Total income tax expense	$	222.0	12.7	%	$	204.6	13.3	%	$	322.9	18.6	%

(1)    The Tax Legislation required our regulated utilities to remeasure their deferred income taxes and we began to amortize the resulting excess protected deferred income taxes beginning in 2018 in accordance with normalization requirements. The decrease in income tax expense related to the amortization of the deferred tax benefits is offset by a decrease in revenue as the benefits are returned to customers, resulting in no impact on net income.

Components of deferred income taxes

The components of deferred income taxes as of December 31 were as follows:

(in millions)	2024		2023
Deferred tax assets
Tax gross up – regulatory items	$	420.1	$	438.6
Future tax benefits	165.4		160.7
Deferred revenues	76.0		84.7
Other	167.9		168.3
Total deferred tax assets	829.4		852.3
Valuation allowance	(1.1)		(5.0)
Net deferred tax assets	$	828.3	$	847.3
Deferred tax liabilities
Property-related	$	4,545.2	$	4,198.0
Investment in affiliates	1,103.9		915.1
Employee benefits and compensation	231.4		227.2
Deferred costs – plant retirements	194.3		199.6
Other	268.2		225.9
Total deferred tax liabilities	6,343.0		5,765.8
Deferred tax liability, net	$	5,514.7	$	4,918.5

Components of deferred tax assets associated with federal and state tax benefit carryforwards

The components of net deferred tax assets associated with federal and state tax benefit carryforwards as of December 31, 2024 and 2023 are summarized in the tables below:

2024 (in millions)	Gross Value		Deferred Tax Effect		Valuation Allowance		Earliest Year of Expiration
Future tax benefits as of December 31, 2024
Federal tax credit	$	—	$	157.9	$	—	2042
State net operating loss	107.5		7.2		(1.1)		2032
Other state benefits	—		0.3		—		2028
Balance as of December 31, 2024	$	107.5	$	165.4	$	(1.1)

2023 (in millions)	Gross Value		Deferred Tax Effect		Valuation Allowance		Earliest Year of Expiration
Future tax benefits as of December 31, 2023
Federal tax credit	$	—	$	153.0	$	—	2042
State net operating loss	62.6		3.8		(1.1)		2032
Other state benefits	—		3.9		(3.9)		2024
Balance as of December 31, 2023	$	62.6	$	160.7	$	(5.0)

Schedule of unrecognized tax benefits roll forward

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:

(in millions)	2024		2023		2022
Balance as of January 1	$	4.6	$	6.3	$	6.8
Additions for tax positions of prior years	—		0.2		0.3
Additions based on tax positions related to the current year	—		—		0.4
Reductions for tax positions of prior years	(0.2)		(1.9)		(1.2)
Balance as of December 31	$	4.4	$	4.6	$	6.3

Roll forward of interest accrued on unrecognized tax benefits

Interest accrued related to unrecognized tax benefits is as follows:

(in millions)	2024		2023		2022
Balance as of January 1	$	0.6	$	0.5	$	0.1
Interest expense related to unrecognized tax benefits	0.3		0.1		0.4
Balance as of December 31	$	0.9	$	0.6	$	0.5

Summary of income tax examinations

As of December 31, 2024, with a few exceptions, we were subject to examination by federal and state or local tax authorities for the 2020 through 2024 tax years in our major operating jurisdictions as follows:

Jurisdiction	Years
Federal	2021–2024
Illinois	2021–2024
Michigan	2020–2024
Minnesota	2020–2024
Wisconsin	2020–2024