Income Taxes

6 Months Ended

Jun. 30, 2016

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The provision for income taxes for earnings from continuing operations is based on an estimated annual effective income tax rate that excludes the impact of significant unusual or infrequently occurring items, discontinued operations or extraordinary items. 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	2016		2015		2016		2015		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(7.9	)	(10.6	)	(16.6	)	(25.3	)	—		—
Production tax credits	(5.7	)	(6.5	)	(5.3	)	(7.2	)	(6.3	)	(6.9	)
Effect of rate-making on property-related differences	(4.9	)	(8.4	)	(8.8	)	(22.3	)	(1.0	)	(0.7	)
Other items, net	0.7		4.1		(2.0	)	5.3		4.5		4.5
Overall income tax rate	17.2	%	13.6	%	2.3	%	(14.5	%)	32.2	%	31.9	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2016		2015		2016		2015		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(8.4	)	(10.2	)	(19.0	)	(25.2	)	—		—
Production tax credits	(6.0	)	(6.4	)	(6.1	)	(7.1	)	(6.4	)	(6.5	)
Effect of rate-making on property-related differences	(5.9	)	(7.0	)	(12.5	)	(16.6	)	(0.9	)	(0.6	)
Other items, net	2.8		4.3		2.6		4.9		4.7		4.4
Overall income tax rate	17.5	%	15.7	%	—	%	(9.0	%)	32.4	%	32.3	%

IPL’s tax benefit riders - Alliant Energy’s and IPL’s effective income tax rates include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing IPL’s tax benefit riders. Refer to Note 2 for additional details of the tax benefit riders.

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2016, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $92.9 million, $62.1 million and $44.1 million, respectively. These increases in non-current deferred tax liabilities were primarily due to property-related differences recorded during the six months ended June 30, 2016.

Carryforwards - At June 30, 2016, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

		Alliant Energy				IPL				WPL
	Earliest Expiration Date	Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets
Federal net operating losses	2030		$769		$264		$349		$117		$311		$109
State net operating losses	2018	747		39		20		1		38		2
Federal tax credits	2022	258		254		93		90		105		105
					$557				$208				$216

IPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The provision for income taxes for earnings from continuing operations is based on an estimated annual effective income tax rate that excludes the impact of significant unusual or infrequently occurring items, discontinued operations or extraordinary items. 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	2016		2015		2016		2015		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(7.9	)	(10.6	)	(16.6	)	(25.3	)	—		—
Production tax credits	(5.7	)	(6.5	)	(5.3	)	(7.2	)	(6.3	)	(6.9	)
Effect of rate-making on property-related differences	(4.9	)	(8.4	)	(8.8	)	(22.3	)	(1.0	)	(0.7	)
Other items, net	0.7		4.1		(2.0	)	5.3		4.5		4.5
Overall income tax rate	17.2	%	13.6	%	2.3	%	(14.5	%)	32.2	%	31.9	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2016		2015		2016		2015		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(8.4	)	(10.2	)	(19.0	)	(25.2	)	—		—
Production tax credits	(6.0	)	(6.4	)	(6.1	)	(7.1	)	(6.4	)	(6.5	)
Effect of rate-making on property-related differences	(5.9	)	(7.0	)	(12.5	)	(16.6	)	(0.9	)	(0.6	)
Other items, net	2.8		4.3		2.6		4.9		4.7		4.4
Overall income tax rate	17.5	%	15.7	%	—	%	(9.0	%)	32.4	%	32.3	%

IPL’s tax benefit riders - Alliant Energy’s and IPL’s effective income tax rates include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing IPL’s tax benefit riders. Refer to Note 2 for additional details of the tax benefit riders.

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2016, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $92.9 million, $62.1 million and $44.1 million, respectively. These increases in non-current deferred tax liabilities were primarily due to property-related differences recorded during the six months ended June 30, 2016.

Carryforwards - At June 30, 2016, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

		Alliant Energy				IPL				WPL
	Earliest Expiration Date	Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets
Federal net operating losses	2030		$769		$264		$349		$117		$311		$109
State net operating losses	2018	747		39		20		1		38		2
Federal tax credits	2022	258		254		93		90		105		105
					$557				$208				$216

WPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The provision for income taxes for earnings from continuing operations is based on an estimated annual effective income tax rate that excludes the impact of significant unusual or infrequently occurring items, discontinued operations or extraordinary items. 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	2016		2015		2016		2015		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(7.9	)	(10.6	)	(16.6	)	(25.3	)	—		—
Production tax credits	(5.7	)	(6.5	)	(5.3	)	(7.2	)	(6.3	)	(6.9	)
Effect of rate-making on property-related differences	(4.9	)	(8.4	)	(8.8	)	(22.3	)	(1.0	)	(0.7	)
Other items, net	0.7		4.1		(2.0	)	5.3		4.5		4.5
Overall income tax rate	17.2	%	13.6	%	2.3	%	(14.5	%)	32.2	%	31.9	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2016		2015		2016		2015		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(8.4	)	(10.2	)	(19.0	)	(25.2	)	—		—
Production tax credits	(6.0	)	(6.4	)	(6.1	)	(7.1	)	(6.4	)	(6.5	)
Effect of rate-making on property-related differences	(5.9	)	(7.0	)	(12.5	)	(16.6	)	(0.9	)	(0.6	)
Other items, net	2.8		4.3		2.6		4.9		4.7		4.4
Overall income tax rate	17.5	%	15.7	%	—	%	(9.0	%)	32.4	%	32.3	%

IPL’s tax benefit riders - Alliant Energy’s and IPL’s effective income tax rates include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing IPL’s tax benefit riders. Refer to Note 2 for additional details of the tax benefit riders.

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2016, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $92.9 million, $62.1 million and $44.1 million, respectively. These increases in non-current deferred tax liabilities were primarily due to property-related differences recorded during the six months ended June 30, 2016.

Carryforwards - At June 30, 2016, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

		Alliant Energy				IPL				WPL
	Earliest Expiration Date	Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets
Federal net operating losses	2030		$769		$264		$349		$117		$311		$109
State net operating losses	2018	747		39		20		1		38		2
Federal tax credits	2022	258		254		93		90		105		105
					$557				$208				$216