12. Income Taxes

Loss before income taxes for the years ended December 31 consisted of the following:


	2013			2012			2011
	(In thousands)
Domestic	$	(28,746	)	$	(17,618	)	$	(10,966	)
Foreign		(535	)		(90	)		34

Loss before income taxes	$	(29,281	)	$	(17,708	)	$	(10,932	)

Income tax expense (benefit) differed from the amounts computed by applying the statutory federal income tax rate of 34% to pretax loss as a result of the following for the years ended December 31:


	2013			2012			2011
	(In thousands)
Income tax provision at statutory rate	$	(9,955	)	$	(6,021	)	$	(3,717	)
Nondeductible items		(32	)		349			25
Change in tax credits		(893	)		39			(202	)
Change in valuation allowance		10,965			5,894			3,963
Other		(85	)		(261	)		(69	)

	$	—		$	—		$	—

At December 31, 2013, the Company had net operating loss carryforwards of approximately $92.6 million which will begin to expire in 2023 through 2033. In addition, at December 31, 2013, the Company had research and development tax credit carryforwards of approximately $2.2 million.

The Company does not expect to utilize any of its net operating loss and tax credit carryforwards in the near term. The Company may have already experienced one or more ownership changes. Depending on the timing of any future utilization of its carryforwards, the Company may be limited as to the amount that can be utilized each year as a result of such previous ownership changes. However, the Company does not believe such limitations will cause its carryforwards to expire unutilized. Future changes in the Company’s stock ownership as well as other changes that may be outside the Company’s control could potentially result in further limitations on the Company’s ability to utilize its net operating loss and tax credit carryforwards.

The effect of temporary differences and carryforwards that give rise to deferred tax assets for the years ended December 31 were as follows:


	2013			2012
	(In thousands)
Net operating loss carryforwards	$	31,989		$	21,569
Research and development tax credit carryforwards		1,654			761
Other		2,369			2,717

Total deferred tax assets		36,012			25,047
Less: Valuation allowance		(36,012	)		(25,047	)

Net deferred tax assets	$	—		$	—

The Company has recorded a full valuation allowance related to its deferred tax assets due to the uncertainty of the ultimate realization of the future benefits from those assets.

The table below summarizes changes in the deferred tax asset valuation allowance:


	Balance at Beginning of Year		Charged to Costs and Expenses		Write-offs		Balance at End of Year
	(In thousands)
Deferred tax valuation allowance:
For year ended December 31, 2011	$	15,190	$	3,963	$	—	$	19,153
For year ended December 31, 2012		19,153		5,894		—		25,047
For year ended December 31, 2013		25,047		10,965		—		36,012

The total balance of unrecognized gross tax benefits for the years ended December 31 was as follows:


	2013		2012			2011
	(In thousands)
Unrecognized tax benefits at beginning of year	$	253	$	267		$	199
Additions (reductions) based on current year tax positions		298		(14	)		68

Unrecognized tax benefits at end of year	$	551	$	253		$	267

The Company classifies applicable interest and penalties on amounts due to tax authorities as a component of the provision for income taxes. The amount of accrued interest and penalties recorded in 2013, 2012 or 2011 was not material. We do not anticipate that the amount of our existing unrecognized tax benefits will significantly increase or decrease within the next 12 months. Due to the presence of net operating loss carryforwards in most jurisdictions, our tax years remain open for examination by U.S. taxing authorities back to 2004.