9. Income Taxes

The components of our income tax benefit in 2015 and 2014 are as follows:


	2015			2014
Current Tax Benefit
Federal	$	—		$	—
State		(585	)		(2,019	)

		(585	)		(2,019	)

Deferred Tax Expense (Benefit)
Federal		—			—
State		—			—

		—			—

Total Tax Benefit	$	(585	)	$	(2,019	)

As of December 31, 2015, we have available unused federal net operating loss (NOL) carry-forwards of $357 million, which will expire in various years from 2018 to 2035. We have New York NOL carry-forwards of $294 with the remainder expiring in various years from 2018 through 2035. We have New Jersey NOL carry-forwards of $3.1 million, which will expire in various years from 2023 through 2035.

As of December 31, 2015, we have Research and Development tax credit carryforwards of $11 million which will expire in various years from 2018 to 2032.

The effective rate differs from the statutory rate of 34% for 2015, 2014 and 2013 primarily due to the following:


	2015			2014			2013
Statutory Rate on pre-tax book loss		(34.00	%)		(34.00	%)		(34.00	%)
Stock option issuance		0.14	%		0.09	%		0.08	%
Sale of NJ NOL’s		1.05	%		2.51	%		0.00	%
Disallowed interest		0.10	%		0.51	%		3.57	%
Derivatives		11.72	%		14.75	%		13.71	%
Expired net operating losses and credits		0.00	%		2.74	%		41.83	%
Utilization of net operating loss		0.00	%		0.00	%		(2.86	%)
State Tax benefit of Sale of NJ NOL		(1.45	%)		(7.37	%)		0.00	%
State Tax benefit — other		(3.85	%)		(2.82	%)		6.21	%
True-ups and adjustments		(0.57	%)		0.02	%		0.44	%
Change in federal valuation allowance		25.42	%		16.22	%		(28.85	%)

		(-1.44	%)		(7.35	%)		0.13	%

The tax effect of temporary differences, net operating loss carry-forwards, and research and experimental tax credit carryforwards as of December 31, 2015 and 2014 is as follows:

Deferred tax assets and valuation allowance:


	December 31,
	2015			2014
	(in thousands)
Current deferred tax asset:
Accrued liabilities	$	111		$	23
Valuation allowance		(111	)		(23	)

Net current deferred tax asset		—			—

Non-current deferred tax assets:
Fixed and intangible assets		11			9
Net operation loss carry-forwards		122,205			121,180
AMT credit carry-forwards		74			74
Capital loss and charitable carry-forwards		13			9
Research and experimental tax credits		11,021			11,021
Stock compensation		586			486
Deferred revenue		22,213			16,621
Interest		6,870			3,414
Valuation allowance	$	(162,993	)	$	(152,814	)

Net non-current deferred tax asset		—			—

Future ownership changes may limit the future utilization of these net operating loss and research and development tax credit carry-forwards as defined by the Internal Revenue Code. We performed an in-depth analysis and determined that the net operating losses and research and development expenses are not limited under Section 382. The net deferred tax asset has been fully offset by a valuation allowance due to our history of taxable losses and uncertainty regarding our ability to generate sufficient taxable income in the future to utilize these deferred tax assets.

We apply the provisions of ASC 740-10-25 which provides recognition criteria and a related measurement model for uncertain tax positions taken or expected to be taken in income tax returns. ASC 740-10-25 requires that a position taken or expected to be taken in a tax return be recognized in the financial statements when it is more likely than not that the position would be sustained upon examination by tax authorities. Tax positions that meet the more likely than not threshold are then measured using a probability weighted approach recognizing the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate settlement. The Company had no tax positions relating to open income tax returns that were considered to be uncertain. Accordingly, we have not recorded a liability for unrecognized tax benefits upon adoption of ASC 740-10-25. There continues to be no liability related to unrecognized tax benefits at December 31, 2015.

The Company’s 2012, 2013 and 2014 Federal, New York and New Jersey tax returns remain subject to examination by the respective taxing authorities. In addition, net operating losses and research tax credits arising from prior years are also subject to examination at the time that they are utilized in future years. Neither the Company’s federal or state tax returns are currently under examination.