Income Taxes

6 Months Ended

Jun. 30, 2018

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended June 30	2018		2017		2018		2017		2018		2017
Statutory federal income tax rate	21.0	%	35.0	%	21.0	%	35.0	%	21.0	%	35.0	%
State income taxes, net of federal benefits	6.5		5.5		7.0		6.5		6.2		5.1
Effect of rate-making on property-related differences	(6.7	)	(9.0	)	(11.5	)	(18.0	)	(2.7	)	(1.9	)
Production tax credits	(5.4	)	(5.9	)	(5.3	)	(6.2	)	(6.8	)	(7.1	)
IPL’s tax benefit riders	(2.1	)	(7.8	)	(4.3	)	(18.6	)	—		—
Other items, net	(1.6	)	0.2		(2.8	)	—		(4.2	)	(0.6	)
Overall income tax rate	11.7	%	18.0	%	4.1	%	(1.3	%)	13.5	%	30.5	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2018		2017		2018		2017		2018		2017
Statutory federal income tax rate	21.0	%	35.0	%	21.0	%	35.0	%	21.0	%	35.0	%
State income taxes, net of federal benefits	7.1		5.5		7.7		6.4		6.2		5.1
Effect of rate-making on property-related differences	(7.2	)	(8.0	)	(12.4	)	(18.0	)	(2.5	)	(1.8	)
Production tax credits	(5.5	)	(5.9	)	(5.3	)	(6.4	)	(6.7	)	(7.0	)
IPL’s tax benefit riders	(2.2	)	(7.8	)	(4.5	)	(19.0	)	—		—
Other items, net	(1.4	)	(2.4	)	(1.5	)	(3.3	)	(2.0	)	(0.6	)
Overall income tax rate	11.8	%	16.4	%	5.0	%	(5.3	%)	16.0	%	30.7	%

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2018, Alliant Energy’s, IPL’s and WPL’s deferred tax liabilities increased (decreased) $28.8 million, ($7.8) million and $17.6 million, respectively. Alliant Energy’s and WPL’s increases were primarily due to property-related differences and the utilization of federal net operating losses, which were partially offset by an increase in federal credit carryforwards. Alliant Energy’s increase was also partially offset by the effects of Iowa tax reform, which is discussed in Note 2. IPL’s decrease was primarily due to the effects of Iowa tax reform and an increase in federal credit carryforwards, which were partially offset by property-related differences and the utilization of federal net operating losses.

Carryforwards - At June 30, 2018, carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy		IPL		WPL
Federal net operating losses	2030-2037		$759		$490		$170
State net operating losses	2018-2038	732		13		22
Federal tax credits	2022-2038	284		127		140

IPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended June 30	2018		2017		2018		2017		2018		2017
Statutory federal income tax rate	21.0	%	35.0	%	21.0	%	35.0	%	21.0	%	35.0	%
State income taxes, net of federal benefits	6.5		5.5		7.0		6.5		6.2		5.1
Effect of rate-making on property-related differences	(6.7	)	(9.0	)	(11.5	)	(18.0	)	(2.7	)	(1.9	)
Production tax credits	(5.4	)	(5.9	)	(5.3	)	(6.2	)	(6.8	)	(7.1	)
IPL’s tax benefit riders	(2.1	)	(7.8	)	(4.3	)	(18.6	)	—		—
Other items, net	(1.6	)	0.2		(2.8	)	—		(4.2	)	(0.6	)
Overall income tax rate	11.7	%	18.0	%	4.1	%	(1.3	%)	13.5	%	30.5	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2018		2017		2018		2017		2018		2017
Statutory federal income tax rate	21.0	%	35.0	%	21.0	%	35.0	%	21.0	%	35.0	%
State income taxes, net of federal benefits	7.1		5.5		7.7		6.4		6.2		5.1
Effect of rate-making on property-related differences	(7.2	)	(8.0	)	(12.4	)	(18.0	)	(2.5	)	(1.8	)
Production tax credits	(5.5	)	(5.9	)	(5.3	)	(6.4	)	(6.7	)	(7.0	)
IPL’s tax benefit riders	(2.2	)	(7.8	)	(4.5	)	(19.0	)	—		—
Other items, net	(1.4	)	(2.4	)	(1.5	)	(3.3	)	(2.0	)	(0.6	)
Overall income tax rate	11.8	%	16.4	%	5.0	%	(5.3	%)	16.0	%	30.7	%

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2018, Alliant Energy’s, IPL’s and WPL’s deferred tax liabilities increased (decreased) $28.8 million, ($7.8) million and $17.6 million, respectively. Alliant Energy’s and WPL’s increases were primarily due to property-related differences and the utilization of federal net operating losses, which were partially offset by an increase in federal credit carryforwards. Alliant Energy’s increase was also partially offset by the effects of Iowa tax reform, which is discussed in Note 2. IPL’s decrease was primarily due to the effects of Iowa tax reform and an increase in federal credit carryforwards, which were partially offset by property-related differences and the utilization of federal net operating losses.

Carryforwards - At June 30, 2018, carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy		IPL		WPL
Federal net operating losses	2030-2037		$759		$490		$170
State net operating losses	2018-2038	732		13		22
Federal tax credits	2022-2038	284		127		140

WPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended June 30	2018		2017		2018		2017		2018		2017
Statutory federal income tax rate	21.0	%	35.0	%	21.0	%	35.0	%	21.0	%	35.0	%
State income taxes, net of federal benefits	6.5		5.5		7.0		6.5		6.2		5.1
Effect of rate-making on property-related differences	(6.7	)	(9.0	)	(11.5	)	(18.0	)	(2.7	)	(1.9	)
Production tax credits	(5.4	)	(5.9	)	(5.3	)	(6.2	)	(6.8	)	(7.1	)
IPL’s tax benefit riders	(2.1	)	(7.8	)	(4.3	)	(18.6	)	—		—
Other items, net	(1.6	)	0.2		(2.8	)	—		(4.2	)	(0.6	)
Overall income tax rate	11.7	%	18.0	%	4.1	%	(1.3	%)	13.5	%	30.5	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2018		2017		2018		2017		2018		2017
Statutory federal income tax rate	21.0	%	35.0	%	21.0	%	35.0	%	21.0	%	35.0	%
State income taxes, net of federal benefits	7.1		5.5		7.7		6.4		6.2		5.1
Effect of rate-making on property-related differences	(7.2	)	(8.0	)	(12.4	)	(18.0	)	(2.5	)	(1.8	)
Production tax credits	(5.5	)	(5.9	)	(5.3	)	(6.4	)	(6.7	)	(7.0	)
IPL’s tax benefit riders	(2.2	)	(7.8	)	(4.5	)	(19.0	)	—		—
Other items, net	(1.4	)	(2.4	)	(1.5	)	(3.3	)	(2.0	)	(0.6	)
Overall income tax rate	11.8	%	16.4	%	5.0	%	(5.3	%)	16.0	%	30.7	%

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2018, Alliant Energy’s, IPL’s and WPL’s deferred tax liabilities increased (decreased) $28.8 million, ($7.8) million and $17.6 million, respectively. Alliant Energy’s and WPL’s increases were primarily due to property-related differences and the utilization of federal net operating losses, which were partially offset by an increase in federal credit carryforwards. Alliant Energy’s increase was also partially offset by the effects of Iowa tax reform, which is discussed in Note 2. IPL’s decrease was primarily due to the effects of Iowa tax reform and an increase in federal credit carryforwards, which were partially offset by property-related differences and the utilization of federal net operating losses.

Carryforwards - At June 30, 2018, carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy		IPL		WPL
Federal net operating losses	2030-2037		$759		$490		$170
State net operating losses	2018-2038	732		13		22
Federal tax credits	2022-2038	284		127		140