Income Taxes

Deferred tax assets and liabilities are the result of temporary differences between the consolidated financial statement carrying values and the tax basis of assets and liabilities. Significant components of net deferred tax assets (liabilities) at December 31, 2014 and 2013 are as follows:



	2014			2013
	(In thousands)
Deferred tax assets:
Net operating loss carryforwards	$	84,587		$	65,814
Statutory depletion carryforwards	9,581			8,658
Asset retirement obligations and other	19,061			22,470
	113,229			96,942
Deferred tax liabilities:
Fair value of derivatives	—			(598		)
Property and equipment	(270,917		)	(229,572		)
	(270,917		)	(230,170		)
Net deferred tax liabilities	$	(157,688	)	$	(133,228	)

Components of net deferred tax liabilities:
Current assets	$	6,911		$	7,581
Non-current liabilities	(164,599		)	(140,809		)
Net deferred tax liabilities	$	(157,688	)	$	(133,228	)

For the years ended December 31, 2014, 2013 and 2012, effective income tax rates were different than the statutory federal income tax rates for the following reasons:



	2014			2013			2012
	(In thousands)
Income tax expense (benefit) at statutory rate of 35%	$	23,999		$	(13,052	)	$	19,989
Tax depletion in excess of basis	(729		)	(518		)	(581		)
Revision of previous tax estimates	(155		)	373			700
State income taxes, net of federal tax effect	1,008			76			1,513
Other	564			693			387
Income tax expense (benefit)	$	24,687		$	(12,428	)	$	22,008

Current	$	227		$	1,614		$	—
Deferred	24,460			(14,042		)	22,008
Income tax expense (benefit)	$	24,687		$	(12,428	)	$	22,008

We derive a tax deduction when options are exercised under our stock option plans. To the extent these tax deductions are used to reduce currently payable taxes in any period, we record a tax benefit for the excess of the tax deduction over cumulative book compensation expense as additional paid-in capital and as a financing cash flow in the accompanying consolidated financial statements. At December 31, 2014, our cumulative tax loss carryforwards were approximately $263.2 million, of which $22 million relates to excess tax benefits from exercise of stock options. The cumulative tax loss carryforwards are scheduled to expire if not utilized between 2025 and 2029.

In assessing the ability to realize deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. If it is more likely than not that some portion or all of the assets will not be realized, the assets are reduced by a valuation allowance. Based on our analysis of future taxable income, no valuation allowance is required.

CWEI and its subsidiaries file federal income tax returns with the United States Internal Revenue Service and state income tax returns in various state tax jurisdictions. As a general rule, the Company’s tax returns for fiscal years after 2010 currently remain subject to examination by appropriate taxing authorities. None of our income tax returns are under examination at this time. We do not have any uncertain tax positions as of December 31, 2014 and 2013.