A reconciliation of income tax expense, computed by applying the federal statutory rate to pre-tax income to our effective income tax expense is as follows:



	2014		2013		2012
	(In thousands)
Income tax expense computed by applying the statutory rate	$	78,029	$	105,514	$	13,791
State income tax, net of federal benefit	6,131		8,290		1,084
Statutory depletion and other	2,503		2,919		1,351
Income tax expense	$	86,663	$	116,723	$	16,226

For the periods indicated, the total provision for income taxes consisted of the following:



	2014		2013		2012
	(In thousands)
Current taxes:
Federal	$	8,594	$	15,845	$	2,084
State	784		146		(1,388		)
	9,378		15,991		696
Deferred taxes:
Federal	68,360		87,839		13,768
State	8,925		12,893		1,762
	77,285		100,732		15,530
Total provision	$	86,663	$	116,723	$	16,226

Deferred tax assets and liabilities are comprised of the following at December 31:



	2014			2013
	(In thousands)
Deferred tax assets:
Allowance for losses and nondeductible accruals	$	55,231		$	77,285
Net operating loss carryforward	54,901			61,055
Alternative minimum tax and research and development tax credit carryforward	25,991			17,258
	136,123			155,598
Deferred tax liability:
Depreciation, depletion, amortization, and impairment	(1,000,811		)	(943,411		)
Net deferred tax liability	(864,688		)	(787,813		)
Current deferred tax asset	11,527			13,585
Non-current—deferred tax liability	$	(876,215	)	$	(801,398	)

Realization of the deferred tax assets are dependent on generating sufficient future taxable income. Although realization is not assured, management believes it is more likely than not that the deferred tax asset will be realized. The amount of the deferred tax asset considered realizable, however, could be reduced in the near-term if estimates of future taxable income are reduced. At December 31, 2014, we have federal net operating loss carryforwards of approximately $128.0 million which expire from 2020 to 2034.

We file income tax returns in the U.S. federal jurisdiction and various states. We are no longer subject to U.S. federal or state income tax examinations by tax authorities for years before 2011. We are currently under examination by the state of Texas for the 2011-2013 return years but have not been made aware of any adjustments that would be material to our financial statements. During 2014, we recognized a tax benefit relating to a research and development tax credit carryforward in conjunction with our BOSS drilling rig activities. Due to the nature and subjectivity surrounding the research and development credit and historical challenges by the IRS against companies who claim the credit, it is our belief that the full amount of the credit may not be eventually allowed by the IRS once we are no longer in an AMT tax paying position. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:



	2014		2013		2012
	(In thousands)
Balance at January 1:	$	—	$	—	$	—
Additions based on tax positions related to current year	410		—		—
Additions for tax positions of prior years	—		—		—
Reductions for tax positions of prior years	—		—		—
Settlements	—		—		—
Balance at December 31:	$	410	$	—	$	—

At December 31, 2014, there was $0.4 million of unrecognized tax benefits that if recognized would affect the annual effective tax rate. We did not have any unrecognized tax benefits in 2013 or 2012.