Income Taxes

Def

erred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred tax assets (liabilities) as of

December

31,

2017

and

2016

are as follows (in thousands):

	December 31
	201 7			201 6

Net operating loss carryforwards	$	21,175		$	32,644
Net operating loss carryforwards of foreign subsidiaries		374			374
Book over tax depreciation		(14	)		(48	)
Stock-based compensation expense		25			38
Other		94			124
Deferred tax assets		21,654			33,132
Valuation allowance for deferred tax assets		(21,654	)		(33,132	)
Deferred tax assets, net of allowance	$	—		$	—

Deferred tax assets are required to be reduced by a valuation allowance if it is more likely than

not

that some portion or all of the deferred tax assets will

not

be realized. Realization of the future benefits related to the deferred tax assets is depe

ndent on many factors, including the Company’s ability to generate taxable income within the near to medium term. Management has considered these factors in determining the valuation allowance for

2017

and

2016

The differences between the provision for

income taxes and income taxes computed using the federal statutory rate for the years ended

December

31,

2017

and

2016

are as follows (in thousands):

	201 7			201 6

Reconciliation of income tax benefit to statutory rate:
Income benefit at sta tutory rate	$	(10	)	$	(528	)
State income taxes (benefit), net of federal income tax benefit		1			(40	)
RTP (ISO expense)		—			38
Permanent differences		11			28
Change in valuation allowance		(11,478	)		890
Remeasurment of Deferreds		11,476			—
Change in state tax rate		—			(345	)
Other		—			(43	)
	$	—		$	—

December

31,

2017,

we had federal net operating loss carryforwards of approximately

$87

million for income tax purposes that begin to expire in

2022

and are subject to the ownership change limitations under Internal Revenue Code Section

382.

We had approximately

million of state net operating loss carryforwards beginning to expire in

2017.