Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2024

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023
Tax-related	$1,000	$934	$885	$831	$115	$103
AROs	418	194	223	160	195	34
Pension and OPEB costs	329	347	163	171	166	176
Assets retired early	181	273	169	259	12	14
Derivatives	80	102	24	34	56	68
Commodity cost recovery	76	120	8	12	68	108
WPL’s Western Wisconsin gas distribution expansion investments	42	44	—	—	42	44
IPL’s Duane Arnold Energy Center purchased power agreement amendment	24	42	24	42	—	—
Other	200	205	72	68	128	137
	$2,350	$2,261	$1,568	$1,577	$782	$684

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023
Tax-related	$589	$566	$286	$299	$303	$267
Cost of removal obligations	359	366	215	242	144	124
Derivatives	47	65	26	34	21	31
Commodity cost recovery	45	48	8	13	37	35
Other	32	85	18	56	14	29
	$1,072	$1,130	$553	$644	$519	$486

IPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023
Tax-related	$1,000	$934	$885	$831	$115	$103
AROs	418	194	223	160	195	34
Pension and OPEB costs	329	347	163	171	166	176
Assets retired early	181	273	169	259	12	14
Derivatives	80	102	24	34	56	68
Commodity cost recovery	76	120	8	12	68	108
WPL’s Western Wisconsin gas distribution expansion investments	42	44	—	—	42	44
IPL’s Duane Arnold Energy Center purchased power agreement amendment	24	42	24	42	—	—
Other	200	205	72	68	128	137
	$2,350	$2,261	$1,568	$1,577	$782	$684

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023
Tax-related	$589	$566	$286	$299	$303	$267
Cost of removal obligations	359	366	215	242	144	124
Derivatives	47	65	26	34	21	31
Commodity cost recovery	45	48	8	13	37	35
Other	32	85	18	56	14	29
	$1,072	$1,130	$553	$644	$519	$486

WPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023
Tax-related	$1,000	$934	$885	$831	$115	$103
AROs	418	194	223	160	195	34
Pension and OPEB costs	329	347	163	171	166	176
Assets retired early	181	273	169	259	12	14
Derivatives	80	102	24	34	56	68
Commodity cost recovery	76	120	8	12	68	108
WPL’s Western Wisconsin gas distribution expansion investments	42	44	—	—	42	44
IPL’s Duane Arnold Energy Center purchased power agreement amendment	24	42	24	42	—	—
Other	200	205	72	68	128	137
	$2,350	$2,261	$1,568	$1,577	$782	$684

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023	September 30, 2024	December 31, 2023
Tax-related	$589	$566	$286	$299	$303	$267
Cost of removal obligations	359	366	215	242	144	124
Derivatives	47	65	26	34	21	31
Commodity cost recovery	45	48	8	13	37	35
Other	32	85	18	56	14	29
	$1,072	$1,130	$553	$644	$519	$486