Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

The components of the pretax loss from operations for the years ended December 31, are as follows (in thousands):

The components of the provision for income taxes for the years ended December 31, is presented in the following table:

Significant components of the Company’s net deferred income taxes for the years ended December 31, are as follows (in thousands):



	2017			2016
Deferred tax assets:
Net operating loss carryforward	$	41,086		$	42,013
Property & equipment	524			690
Inventory	58			1,735
Stock options	8,195			7,208
Intangible assets, definite-lived	42			220
General business credit	6,651			3,984
Deferred revenue	253			370
Other	45			121
Valuation allowance	(56,854		)	(56,341		)
Deferred tax assets	$	—		$	—

The difference between the U.S. federal statutory income tax rate and the Company’s effective tax rate for years ending December 31, is as follows:



	2017		2016		2015
U.S. federal statutory income tax rate	(34.00	)%	(34.00	)%	(34.00	)%
State taxes, net of federal tax benefit	(2.62	)	(1.69	)	(2.93	)
Permanent and other differences	(2.31	)	(0.17	)	0.11
Change in tax rates	(1.02	)	0.67		—
Tax rate differential	8.99		8.62		0.42
Tax cuts and jobs act	38.46		—		—
Unrecognized tax benefits	1.20		1.09		0.40
Nondeductible equity and other compensation	(4.31	)	1.17		2.86
Limitation on net operating losses due to §382	—		—		—
Credit for increased research activities	(4.42	)	(3.31	)	(2.67	)
Change in Valuation allowance	0.81		28.02		35.81
	0.78	%	0.40	%	—	%

as follows (in thousands):



	2017		2016		2015
Balance at beginning of year	$	1,101	$	343	$	161
Increases for prior positions	97		37		—
Increases for current year positions	943		721		182
Other increases	—		—		—
Decreases due to settlements	—		—		—
Expiration of the statute of limitations for the assessment of taxes	—		—		—
Other decreases	—		—		—
Balance at end of year	$	2,141	$	1,101	$	343