12. INCOME TAXES

A reconciliation of income tax expense at the statutory rate to income tax expense at our effective tax rate is as follows:


	2016		2015		2014
Tax Expense (Benefit) Computed at 34 % of Pretax Income (Loss)	$	(6,595,452)	$	(4,903,000)	$	(7,251,000)
Foreign Income Tax Expense		(404,527)		—		—
Effect of Change in Valuation Allowance		(6,595,452)		(4,903,000)		(7,251,000)
Total Income Tax Expense	$	404,527	$	—	$	—

The details of the net deferred tax asset are as follows:


	December 31,
	2016		2015
Deferred tax assets:
Net Operating Loss Carryforward	$	51,463,000	$	52,669,000
Stock Based Compensation		7,704,000		4,223,000
Deferred Revenue		6,478,000		5,920,000
General Business Credit		6,146,000		5,741,000
Accrued Expenses		605,000		511,000
Inventories		494,000		163,000
Book over Tax Depreciation		61,000		47,000
Allowance for Doubtful Accounts		2,000		26,000
Total Deferred Tax Assets		72,953,000		69,300,000
Deferred Tax Liabilities:
Goodwill & Intangible Assets		137,000		167,000
Prepaid Expenses		182,000		119,000
Total Deferred Tax Liabilities		319,000		286,000
Subtotal		72,634,000		69,014,000
Valuation Allowance		(72,634,000)		(69,014,000)
Net Deferred Tax Asset	$	—	$	—

Deferred tax assets result primarily from net operating loss carryforwards. For tax purposes, we have net operating loss carryforwards of approximately $151,400,000 that expire between 2018 and 2036.

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will be realized upon the generation of future taxable income during the periods in which those temporary differences become deductible. We recognized $404,527 in foreign income taxes paid for the year ended December 31, 2016. We recognized no income tax expense or benefit for the years ended December 31, 2015 and 2014. While we anticipate generating income within the next year or two, we expect to incur operating losses until our drug products are marketed and generating sufficient profits to offset our operating expenses. Considered together with our limited history of operating income and our net losses in 2016, 2015 and 2014, management has placed a full valuation allowance against the net deferred tax assets as of December 31, 2016 and 2015. The portion of the valuation allowance resulting from excess tax benefits on share based compensation that would be credited directly to contributed capital if recognized in subsequent periods is $5.4 million.

The Company accounts for its uncertain tax positions in accordance with ASC 740‑10, Income Taxes and the amount of unrecognized tax benefits related to tax positions is not significant at December 31, 2016 and 2015.