Regulatory Matters

3 Months Ended

Mar. 31, 2021

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

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

	Alliant Energy		IPL		WPL
	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020
Tax-related	$901	$890	$853	$843	$48	$47
Pension and OPEB costs	570	580	286	291	284	289
Asset retirement obligations	120	119	82	81	38	38
Assets retired early	108	113	74	77	34	36
IPL’s DAEC PPA amendment	108	110	108	110	—	—
WPL’s Western Wisconsin gas distribution expansion investments	55	55	—	—	55	55
Derivatives	13	26	6	13	7	13
Other	132	117	85	68	47	49
	$2,007	$2,010	$1,494	$1,483	$513	$527

Other - In February 2021, portions of the central and southern U.S., including Alliant Energy’s service territories, experienced a prolonged period of very cold temperatures and a series of winter storms. These events created significant volatility and increases in commodity prices caused by higher demand for electricity and natural gas and disruptions in commodity supply, resulting in IPL under-recovering its natural gas costs. In March 2021, IPL received approval from the IUB to spread recovery of these higher natural gas costs from its retail customers through December 2021. As of March 31, 2021, IPL’s cumulative under-collection of these natural gas costs was $20 million, which is included in “Other” regulatory assets in the above table. The extreme temperatures in February 2021 did not impact WPL’s natural gas costs and IPL’s and WPL’s fuel-related costs to the extent of IPL’s natural gas costs.

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

	Alliant Energy		IPL		WPL
	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020
Tax-related	$685	$732	$327	$331	$358	$401
Cost of removal obligations	371	367	242	238	129	129
Electric transmission cost recovery	67	68	40	39	27	29
WPL’s West Riverside liquidated damages	38	38	—	—	38	38
Derivatives	26	28	18	25	8	3
Other	68	73	34	43	34	30
	$1,255	$1,306	$661	$676	$594	$630

Tax-related - Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities are primarily related to excess deferred tax benefits resulting from the remeasurement of accumulated deferred income taxes caused by Federal Tax Reform. During the three months ended March 31, 2021, Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities decreased primarily due to returning a portion of these excess deferred tax benefits back to customers.

IPL [Member]

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

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

	Alliant Energy		IPL		WPL
	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020
Tax-related	$901	$890	$853	$843	$48	$47
Pension and OPEB costs	570	580	286	291	284	289
Asset retirement obligations	120	119	82	81	38	38
Assets retired early	108	113	74	77	34	36
IPL’s DAEC PPA amendment	108	110	108	110	—	—
WPL’s Western Wisconsin gas distribution expansion investments	55	55	—	—	55	55
Derivatives	13	26	6	13	7	13
Other	132	117	85	68	47	49
	$2,007	$2,010	$1,494	$1,483	$513	$527

Other - In February 2021, portions of the central and southern U.S., including Alliant Energy’s service territories, experienced a prolonged period of very cold temperatures and a series of winter storms. These events created significant volatility and increases in commodity prices caused by higher demand for electricity and natural gas and disruptions in commodity supply, resulting in IPL under-recovering its natural gas costs. In March 2021, IPL received approval from the IUB to spread recovery of these higher natural gas costs from its retail customers through December 2021. As of March 31, 2021, IPL’s cumulative under-collection of these natural gas costs was $20 million, which is included in “Other” regulatory assets in the above table. The extreme temperatures in February 2021 did not impact WPL’s natural gas costs and IPL’s and WPL’s fuel-related costs to the extent of IPL’s natural gas costs.

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

	Alliant Energy		IPL		WPL
	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020
Tax-related	$685	$732	$327	$331	$358	$401
Cost of removal obligations	371	367	242	238	129	129
Electric transmission cost recovery	67	68	40	39	27	29
WPL’s West Riverside liquidated damages	38	38	—	—	38	38
Derivatives	26	28	18	25	8	3
Other	68	73	34	43	34	30
	$1,255	$1,306	$661	$676	$594	$630

Tax-related - Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities are primarily related to excess deferred tax benefits resulting from the remeasurement of accumulated deferred income taxes caused by Federal Tax Reform. During the three months ended March 31, 2021, Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities decreased primarily due to returning a portion of these excess deferred tax benefits back to customers.

WPL [Member]

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

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

	Alliant Energy		IPL		WPL
	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020
Tax-related	$901	$890	$853	$843	$48	$47
Pension and OPEB costs	570	580	286	291	284	289
Asset retirement obligations	120	119	82	81	38	38
Assets retired early	108	113	74	77	34	36
IPL’s DAEC PPA amendment	108	110	108	110	—	—
WPL’s Western Wisconsin gas distribution expansion investments	55	55	—	—	55	55
Derivatives	13	26	6	13	7	13
Other	132	117	85	68	47	49
	$2,007	$2,010	$1,494	$1,483	$513	$527

Other - In February 2021, portions of the central and southern U.S., including Alliant Energy’s service territories, experienced a prolonged period of very cold temperatures and a series of winter storms. These events created significant volatility and increases in commodity prices caused by higher demand for electricity and natural gas and disruptions in commodity supply, resulting in IPL under-recovering its natural gas costs. In March 2021, IPL received approval from the IUB to spread recovery of these higher natural gas costs from its retail customers through December 2021. As of March 31, 2021, IPL’s cumulative under-collection of these natural gas costs was $20 million, which is included in “Other” regulatory assets in the above table. The extreme temperatures in February 2021 did not impact WPL’s natural gas costs and IPL’s and WPL’s fuel-related costs to the extent of IPL’s natural gas costs.

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

	Alliant Energy		IPL		WPL
	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020	March 31, 2021	December 31, 2020
Tax-related	$685	$732	$327	$331	$358	$401
Cost of removal obligations	371	367	242	238	129	129
Electric transmission cost recovery	67	68	40	39	27	29
WPL’s West Riverside liquidated damages	38	38	—	—	38	38
Derivatives	26	28	18	25	8	3
Other	68	73	34	43	34	30
	$1,255	$1,306	$661	$676	$594	$630

Tax-related - Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities are primarily related to excess deferred tax benefits resulting from the remeasurement of accumulated deferred income taxes caused by Federal Tax Reform. During the three months ended March 31, 2021, Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities decreased primarily due to returning a portion of these excess deferred tax benefits back to customers.