12. Income taxes

12 Months Ended

Dec. 31, 2016

Notes to Financial Statements

Income taxes - Note 12

12. INCOME TAXES

A provision for income taxes has not been recorded for 2016, 2015 and 2014, due to the valuation allowances placed against the net operating losses and deferred tax assets arising during such periods. A valuation allowance has been recorded for all deferred tax assets. Based on our history of losses since inception, the available objective evidence creates sufficient uncertainty regarding the realizability of the deferred tax assets.

At December 31, 2016, we have net operating loss carryforwards of approximately $371.6 million for federal income tax reporting purposes. In addition, we have research and development tax credits of $7.0 million. The net operating loss carryforwards and research and development credits available to offset future taxable income, if any, will expire in varying amounts from 2018 to 2036, if not previously used.

In addition to the tax benefits above, we have $310,000 of capital loss carryforwards that are scheduled to expire in 2017. In certain circumstances, as specified in the Internal Revenue Code, a 50% or more ownership change by certain combinations of our shareholders during any three year period would result in limitations on our ability to use a portion of our net operating loss carryforwards.

Deferred tax assets are summarized as follows (in thousands):

		December 31,
		2016		2015
Deferred tax assets, current
Reserves	$	2,351	$	2,581
Other		910		749
Total gross deferred tax assets, current		3,261		3,330
Deferred tax assets, non-current
Net operating loss carryforwards		126,335		122,281
R&D credit carryforwards		6,998		6,747
Depreciation/amortization deferred		20,024		20,848
Deferred revenue		2,091		-
Other		8,135		7,954
Total gross deferred tax assets, non-current		163,583		157,830
Net deferred taxes before valuation allowance		166,844		161,160
Less: Valuation allowance		(166,844)		(161,160)
Deferred tax assets	$	-	$	-

The valuation allowance, permanent items, and the research and development credit carryforwards account for substantially all of the difference between our effective income tax rate and the federal statutory tax rate of 34%.

Certain net operating losses arise from the deductibility for tax purposes of compensation under nonqualified stock options equal to the difference between the fair value of the stock on the date of exercise and the exercise price of the options. For financial reporting purposes, the tax effect of this deduction, when recognized, is accounted for as a credit to shareholders' equity.

We did not have any unrecognized tax benefits at December 31, 2016 or 2015.

We recognize interest accrued and penalties related to unrecognized tax benefits in tax expense. During the years ended December 31, 2016, 2015, and 2014, we did not recognized any interest or penalties.

We file income tax returns in the U.S. federal jurisdiction and various states. Due to our operating loss and credit carryforwards, the U.S. federal statute of limitations remains open for 1998 and onward.