Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2022

Regulatory Assets [Line Items]

Schedule of Regulatory Assets

At December 31, regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Tax-related	$929	$934	$848	$884	$81	$50
Pension and OPEB costs	392	462	197	228	195	234
Commodity cost recovery	160	42	1	2	159	40
AROs	151	128	110	89	41	39
Derivatives	84	8	48	4	36	4
Assets retired early	70	92	53	66	17	26
IPL’s DAEC PPA amendment	66	90	66	90	—	—
WPL’s Western Wisconsin gas distribution expansion investments	48	52	—	—	48	52
Other	146	132	63	80	83	52
	$2,046	$1,940	$1,386	$1,443	$660	$497

Assets Retired Early

Details regarding the recovery of the remaining net book value of these assets from IPL’s and WPL’s customers are as follows (dollars in millions):

Entity	Asset	Retirement Date	Regulatory Asset Balance as of Dec. 31, 2022	Recovery	Regulatory Approval
IPL	Sutherland Units 1 and 3	2017	$16	Return of and return on remaining net book value through 2027	IUB and FERC
IPL	M.L. Kapp Unit 2	2018	13	Return of and return on remaining net book value through 2029	IUB and FERC
IPL	Analog electric meters	2019	24	Return of remaining net book value through 2028	IUB and FERC
WPL	Edgewater Unit 4	2018	17	Return of and return on remaining net book value through 2028	PSCW and FERC

Schedule of Regulatory Liabilities

At December 31, regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Tax-related	$579	$585	$303	$312	$276	$273
Cost of removal obligations	398	384	259	252	139	132
Derivatives	210	166	115	77	95	89
Commodity cost recovery	40	17	38	15	2	2
WPL’s West Riverside liquidated damages	32	36	—	—	32	36
Electric transmission cost recovery	20	51	10	27	10	24
Other	45	32	29	8	16	24
	$1,324	$1,271	$754	$691	$570	$580

IPL [Member]

Regulatory Assets [Line Items]

Schedule of Regulatory Assets

At December 31, regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Tax-related	$929	$934	$848	$884	$81	$50
Pension and OPEB costs	392	462	197	228	195	234
Commodity cost recovery	160	42	1	2	159	40
AROs	151	128	110	89	41	39
Derivatives	84	8	48	4	36	4
Assets retired early	70	92	53	66	17	26
IPL’s DAEC PPA amendment	66	90	66	90	—	—
WPL’s Western Wisconsin gas distribution expansion investments	48	52	—	—	48	52
Other	146	132	63	80	83	52
	$2,046	$1,940	$1,386	$1,443	$660	$497

Assets Retired Early

Details regarding the recovery of the remaining net book value of these assets from IPL’s and WPL’s customers are as follows (dollars in millions):

Entity	Asset	Retirement Date	Regulatory Asset Balance as of Dec. 31, 2022	Recovery	Regulatory Approval
IPL	Sutherland Units 1 and 3	2017	$16	Return of and return on remaining net book value through 2027	IUB and FERC
IPL	M.L. Kapp Unit 2	2018	13	Return of and return on remaining net book value through 2029	IUB and FERC
IPL	Analog electric meters	2019	24	Return of remaining net book value through 2028	IUB and FERC
WPL	Edgewater Unit 4	2018	17	Return of and return on remaining net book value through 2028	PSCW and FERC

Schedule of Regulatory Liabilities

At December 31, regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Tax-related	$579	$585	$303	$312	$276	$273
Cost of removal obligations	398	384	259	252	139	132
Derivatives	210	166	115	77	95	89
Commodity cost recovery	40	17	38	15	2	2
WPL’s West Riverside liquidated damages	32	36	—	—	32	36
Electric transmission cost recovery	20	51	10	27	10	24
Other	45	32	29	8	16	24
	$1,324	$1,271	$754	$691	$570	$580

WPL [Member]

Regulatory Assets [Line Items]

Schedule of Regulatory Assets

At December 31, regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Tax-related	$929	$934	$848	$884	$81	$50
Pension and OPEB costs	392	462	197	228	195	234
Commodity cost recovery	160	42	1	2	159	40
AROs	151	128	110	89	41	39
Derivatives	84	8	48	4	36	4
Assets retired early	70	92	53	66	17	26
IPL’s DAEC PPA amendment	66	90	66	90	—	—
WPL’s Western Wisconsin gas distribution expansion investments	48	52	—	—	48	52
Other	146	132	63	80	83	52
	$2,046	$1,940	$1,386	$1,443	$660	$497

Assets Retired Early

Details regarding the recovery of the remaining net book value of these assets from IPL’s and WPL’s customers are as follows (dollars in millions):

Entity	Asset	Retirement Date	Regulatory Asset Balance as of Dec. 31, 2022	Recovery	Regulatory Approval
IPL	Sutherland Units 1 and 3	2017	$16	Return of and return on remaining net book value through 2027	IUB and FERC
IPL	M.L. Kapp Unit 2	2018	13	Return of and return on remaining net book value through 2029	IUB and FERC
IPL	Analog electric meters	2019	24	Return of remaining net book value through 2028	IUB and FERC
WPL	Edgewater Unit 4	2018	17	Return of and return on remaining net book value through 2028	PSCW and FERC

Schedule of Regulatory Liabilities

At December 31, regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Tax-related	$579	$585	$303	$312	$276	$273
Cost of removal obligations	398	384	259	252	139	132
Derivatives	210	166	115	77	95	89
Commodity cost recovery	40	17	38	15	2	2
WPL’s West Riverside liquidated damages	32	36	—	—	32	36
Electric transmission cost recovery	20	51	10	27	10	24
Other	45	32	29	8	16	24
	$1,324	$1,271	$754	$691	$570	$580