Income Taxes

6 Months Ended

Jun. 30, 2015

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	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.6	)	(11.9	)	(25.3	)	(36.6	)	—		—
Effect of rate-making on property-related differences	(8.4	)	(4.8	)	(22.3	)	(14.4	)	(0.7	)	(0.2	)
Production tax credits	(6.5	)	(6.1	)	(7.2	)	(8.0	)	(6.7	)	(5.8	)
Other items, net	4.1		4.8		4.1		4.6		4.6		5.0
Overall income tax rate	13.6	%	17.0	%	(15.7	%)	(19.4	%)	32.2	%	34.0	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.2	)	(11.9	)	(25.2	)	(32.8	)	—		—
Effect of rate-making on property-related differences	(7.0	)	(5.1	)	(16.6	)	(13.0	)	(0.6	)	(0.7	)
Production tax credits	(6.4	)	(6.5	)	(7.2	)	(8.2	)	(6.4	)	(6.2	)
Other items, net	4.3		4.7		4.2		4.6		4.7		4.9
Overall income tax rate	15.7	%	16.2	%	(9.8	%)	(14.4	%)	32.7	%	33.0	%

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.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s effective income tax rates are impacted by the effect of rate-making principles on certain property-related differences for which deferred tax is not recognized in the income statement, substantially all of which relates to IPL. The increased benefits from property-related differences recognized during the three and six months ended June 30, 2015 were primarily due to additional repairs deductions.

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2015, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $128.0 million, $77.4 million and $44.9 million, respectively. These increases in non-current deferred tax liabilities were primarily due to utilization of federal net operating loss carryforwards, and property-related differences recorded during the six months ended June 30, 2015, including an increase in qualifying repairs expenditures.

Carryforwards - At June 30, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$845		$290	2029
State net operating losses	860		44		2018
Federal tax credits	222		218		2022
				$552

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$396		$136	2029
State net operating losses	265		14		2018
Federal tax credits	77		75		2022
				$225

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$342		$117	2029
State net operating losses	170		8		2018
Federal tax credits	86		85		2022
				$210

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	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.6	)	(11.9	)	(25.3	)	(36.6	)	—		—
Effect of rate-making on property-related differences	(8.4	)	(4.8	)	(22.3	)	(14.4	)	(0.7	)	(0.2	)
Production tax credits	(6.5	)	(6.1	)	(7.2	)	(8.0	)	(6.7	)	(5.8	)
Other items, net	4.1		4.8		4.1		4.6		4.6		5.0
Overall income tax rate	13.6	%	17.0	%	(15.7	%)	(19.4	%)	32.2	%	34.0	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.2	)	(11.9	)	(25.2	)	(32.8	)	—		—
Effect of rate-making on property-related differences	(7.0	)	(5.1	)	(16.6	)	(13.0	)	(0.6	)	(0.7	)
Production tax credits	(6.4	)	(6.5	)	(7.2	)	(8.2	)	(6.4	)	(6.2	)
Other items, net	4.3		4.7		4.2		4.6		4.7		4.9
Overall income tax rate	15.7	%	16.2	%	(9.8	%)	(14.4	%)	32.7	%	33.0	%

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.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s effective income tax rates are impacted by the effect of rate-making principles on certain property-related differences for which deferred tax is not recognized in the income statement, substantially all of which relates to IPL. The increased benefits from property-related differences recognized during the three and six months ended June 30, 2015 were primarily due to additional repairs deductions.

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2015, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $128.0 million, $77.4 million and $44.9 million, respectively. These increases in non-current deferred tax liabilities were primarily due to utilization of federal net operating loss carryforwards, and property-related differences recorded during the six months ended June 30, 2015, including an increase in qualifying repairs expenditures.

Carryforwards - At June 30, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$845		$290	2029
State net operating losses	860		44		2018
Federal tax credits	222		218		2022
				$552

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$396		$136	2029
State net operating losses	265		14		2018
Federal tax credits	77		75		2022
				$225

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$342		$117	2029
State net operating losses	170		8		2018
Federal tax credits	86		85		2022
				$210

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	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.6	)	(11.9	)	(25.3	)	(36.6	)	—		—
Effect of rate-making on property-related differences	(8.4	)	(4.8	)	(22.3	)	(14.4	)	(0.7	)	(0.2	)
Production tax credits	(6.5	)	(6.1	)	(7.2	)	(8.0	)	(6.7	)	(5.8	)
Other items, net	4.1		4.8		4.1		4.6		4.6		5.0
Overall income tax rate	13.6	%	17.0	%	(15.7	%)	(19.4	%)	32.2	%	34.0	%

	Alliant Energy				IPL				WPL
Six Months Ended June 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.2	)	(11.9	)	(25.2	)	(32.8	)	—		—
Effect of rate-making on property-related differences	(7.0	)	(5.1	)	(16.6	)	(13.0	)	(0.6	)	(0.7	)
Production tax credits	(6.4	)	(6.5	)	(7.2	)	(8.2	)	(6.4	)	(6.2	)
Other items, net	4.3		4.7		4.2		4.6		4.7		4.9
Overall income tax rate	15.7	%	16.2	%	(9.8	%)	(14.4	%)	32.7	%	33.0	%

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.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s effective income tax rates are impacted by the effect of rate-making principles on certain property-related differences for which deferred tax is not recognized in the income statement, substantially all of which relates to IPL. The increased benefits from property-related differences recognized during the three and six months ended June 30, 2015 were primarily due to additional repairs deductions.

Deferred Tax Assets and Liabilities - For the six months ended June 30, 2015, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $128.0 million, $77.4 million and $44.9 million, respectively. These increases in non-current deferred tax liabilities were primarily due to utilization of federal net operating loss carryforwards, and property-related differences recorded during the six months ended June 30, 2015, including an increase in qualifying repairs expenditures.

Carryforwards - At June 30, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$845		$290	2029
State net operating losses	860		44		2018
Federal tax credits	222		218		2022
				$552

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$396		$136	2029
State net operating losses	265		14		2018
Federal tax credits	77		75		2022
				$225

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$342		$117	2029
State net operating losses	170		8		2018
Federal tax credits	86		85		2022
				$210