9. Income Taxes

The components of the gross deferred tax asset and related valuation allowance at December 31 were as follows:


	2017		2016
Deferred tax assets:
Net operating loss carryforward	$	30,813,509	$	34,451,814
Capitalized start-up costs		1,695,688		2,708,479
Patent amortization		135,358		216,203
Research and orphan drug credits		21,293,509		14,988,522
Deferred rent		71,938		123,744
Deferred compensation		2,274,885		2,107,964
Other		69,906		70,511
Total gross deferred tax assets		56,354,793		54,667,237
Valuation allowance		(56,354,793)		(54,667,237)
Deferred tax assets		—		—
Deferred tax liabilities:
Depreciation		—		—
Total deferred tax liabilities		—		—

Net deferred tax assets	$	—	$	—

Based on the Company’s operating history and management’s expectation regarding future profitability, management believes the realization of the Company’s deferred tax assets does not meet the more-likely-than-not criteria under ASC 740, Income Taxes. Accordingly, a full valuation allowance has been established as of December 31, 2017 and 2016.

On December 22, 2017, the Tax Cuts and Jobs Acts (the “TCJA”) was enacted into law. The TCJA contains several key tax provisions including the reduction of the corporate income tax rate from 35% to 21% effective January 1, 2018, as well as a variety of other changes, including the limitation of the tax deductibility of interest expense, acceleration of expensing of certain business assets and reductions in the amount of executive pay that can qualify as a tax deduction. ASC 740 requires the Company to recognize the effect of the tax law changes in the period of enactment. The Company re-measured certain of its U.S. deferred tax assets and liabilities, based on the rates at which they are expected to reverse in the future. The tax benefit recorded related to the re-measurement of the deferred tax balance was $15.2 million, which was offset by the related valuation allowance. The SEC staff has issued Staff Accounting Bulletin (“SAB”) 118, which will allow the Company to record provisional amounts during a measurement period which is similar to the measurement period used when accounting for business combinations. While the company has substantially completed the provisional analysis of the income tax effects of this recent tax reform legislation, and recorded a reasonable estimate of such effects, the ultimate impact may differ from these provisional amounts, possibly materially, due to, among other things, further refinement of our calculations, additional analysis, changes in assumptions, and actions we may take as a result of the TCJA.

As of December 31, 2017, the Company had $112.0 million of U.S. Federal and state net operating losses, $8.0 million of research and development tax credits and $13.3 million of orphan drug tax credits available to carry forward. A portion of the net operating loss carryforwards will begin to expire in 2026, the research and development tax credits in 2023 and the orphan drug tax credit in 2033.

The Company’s tax attributes, including net operating losses and credits, are subject to any ownership changes as defined under Internal Revenue Code Sections 382 and 383. A change in ownership could affect the Company’s ability to utilize its net operating losses and credits. As of December 31, 2017, the Company does not believe that an ownership change has occurred. Any future ownership changes may cause a limitation on the Company’s ability to utilize existing tax attributes.

The Company files income tax returns in the U.S. federal jurisdiction and in the State of Maryland. The Company’s federal income tax returns for tax years 2003 and after remain subject to examination by the U.S. Internal Revenue Service. The Company’s Maryland income tax returns for the tax years 2006 and thereafter remain subject to examination by the Comptroller of Maryland. In addition, all of the net operating losses, research and development tax credit and orphan drug credit carryforwards that may be used in future years are still subject to adjustment.

The Company did not have unrecognized tax benefits as of December 31, 2017 and 2016, and does not anticipate this to change significantly over the next 12 months. The Company will recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. Reconciliations between the statutory federal income tax rate and the effective income tax rate of income tax expense is as follows as of December 31:


	2017		2016		2015
U.S. Federal statutory tax rate	34.0	%	34.0	%	34.0	%
State taxes	4.4		4.6		3.7
Research credit	1.3		1.0		5.6
Orphan drug credit	11.5		9.0		11.5
Other	0.3		—		—
Stock-based compensation	(0.7)		(0.7)		(1.8)
Change in valuation allowance	(5.1)		(47.9)		(53.0)
Effective change due to corporate tax rate reduction	(45.7)		—		—
Provision for income taxes	—	%	—	%	—	%