Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2023

Regulatory Assets [Line Items]

Regulatory Assets

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

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Regulatory Liabilities

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

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

IPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

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

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Regulatory Liabilities

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

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

WPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

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

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Regulatory Liabilities

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

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570