(4)	Income Taxes

Our income tax benefit was $338.7 million for the year ended December 31, 2015 compared to income tax expense of $396.5 million in 2014 and income tax expense of $33.9 million in 2013. Reconciliation between the statutory federal income tax rate and our effective income tax rate is as follows:


	Year Ended December 31,
	2015		2014			2013
Federal statutory tax rate	35.0	%		35.0	%		35.0	%
State	4.3			3.1			(2.3	)
State apportionment rate change	(0.2	)		(0.2	)		(14.9	)
Non-deductible executive compensation	(0.1	)		0.2			0.7
Valuation allowances	(6.8	)		0.2			3.5
Other	¾			0.2			0.6
Consolidated effective tax rate	32.2	%		38.5	%		22.6	%

Income tax (benefit) expense attributable to income before income taxes consists of the following (in thousands):

		2015								2014						2013
		Current	Deferred			Total			Current		Deferred		Total		Current			Deferred			Total
U.S. federal	$	¾	$	(328,257	)	$	(328,257	)	$	¾	$	361,152	$	361,152	$	¾		$	58,527		$	58,527
U.S. state and local		29		(10,449	)		(10,420	)		1		35,350		35,351		(143	)		(24,527	)		(24,670	)
Total	$	29	$	(338,706	)	$	(338,677	)	$	1	$	396,502	$	396,503	$	(143	)	$	34,000		$	33,857

Significant components of deferred tax assets and liabilities are as follows:

	December 31,
	2015			2014
	(in thousands)
Deferred tax assets:
Net operating loss carryforward	$	173,503		$	176,812
Deferred compensation		45,413			73,942
Equity compensation		25,940			25,833
AMT credits and other credits		4,437			4,447
Asset retirement obligation		101,142			109,808
Cumulative mark-to-market loss		¾			649
Other		10,163			10,908
Valuation allowances:
Federal		(42,500	)		¾
State, net of federal benefit		(41,516	)		(8,800	)
Deferred compensation plans and other		(3,607	)		(7,799	)
Total deferred tax assets		272,975			385,800
Deferred tax liabilities:
Depreciation, depletion and investments		(940,482	)		(1,342,038	)
Cumulative mark-to-market gain		(109,845	)		(154,183	)
Other		(595	)		(2,660	)
Total deferred tax liabilities		(1,050,922	)		(1,498,881	)
Net deferred tax liability	$	(777,947	)	$	(1,113,081	)

At December 31, 2015, deferred tax liabilities exceeded deferred tax assets by $777.9 million. As of December 31, 2015, we have a valuation allowance of $3.1 million on the deferred tax asset related to our deferred compensation plan for planned future distributions to certain executives to the extent that their estimated future compensation plus distribution amounts would exceed the $1.0 million deductible limit provided under I.R.C. Section 162(m). During 2015, we adjusted our state net operating loss and credit carryforwards by a total of $32.7 million. This amount includes $15.6 million in net operating loss carryforwards for Louisiana, Mississippi, Oklahoma and West Virginia and establishes a full valuation for these states where we do not expect to generate any taxable income in the future due to completed or anticipated sales. We established a valuation allowance in 2015 related to our Pennsylvania net operating loss carryforwards of $16.0 million due to the low commodity price environment and the limitation Pennsylvania places on future utilization of net operating loss carryforwards. We also recorded a $1.0 million valuation allowance related to our Texas Margin Tax credit carryforward. In addition, during 2015 we have recorded a valuation allowance of $42.5 million related to our federal net operating loss carryforwards which we expect will expire unused based exclusively on our estimated turn of temporary difference in the next four years.

At December 31, 2015, we had regular net operating loss (“NOL”) carryforwards of $620.6 million and alternative minimum tax (“AMT”) NOL carryforwards of $539.3 million that expire between 2018 and 2035. Our federal deferred tax asset related to regular NOL carryforwards at December 31, 2015 was $123.5 million, which is net of the Accounting Standards Codification 718, “Stock Compensation” reduction for unrealized benefits, related to NOL’s created by excess tax deductions that have not generated current tax benefits. At December 31, 2015, we have AMT credit carryforwards of $665,000 that are not subject to limitation or expiration.

We file consolidated tax returns in the United States federal jurisdiction. We file separate company state income tax returns in Louisiana, Mississippi, Pennsylvania and Virginia and file consolidated or unitary state income tax returns in Oklahoma, Texas and West Virginia. We are subject to U.S. Federal income tax examinations for the years 2012 and after and we are subject to various state tax examinations for years 2011 and after. We have not extended the statute of limitation period in any income tax jurisdiction. Our policy is to recognize interest related to income tax expense in interest expense and penalties in general and administrative expense. We do not have any accrued interest or penalties related to tax amounts as of December 31, 2015. Throughout 2015, our unrecognized tax benefits were not material.