	Year Ended December 31,
	2019		2018
U.S. operations	$	18,562,738	$	38,979,638
Non-U.S. operations		2,015,893		6,341,308
Net loss before income tax benefit	$	20,578,631	$	45,320,946

	Year Ended December 31,
	2019		2018
U.S. federal
Current	$	—	$	271,356
Deferred		45,465		4,309,534
US state and local
Current		—		(1,464	)
Deferred		13,035		1,570,368
Income tax benefit	$	58,500	$	6,149,794

Reconciliation between the effect of applying the federal statutory rate and the effective income tax rate used to calculate the Company’s income tax benefit is as follows:

	Year Ended December 31,
	2019			2018
Federal statutory rate		21.00	%		21.00	%
State income taxes, net of federal benefit		3.12			4.53
Foreign income tax rate differential		(0.01	)		(0.15	)
Stock compensation		(0.93	)		(0.16	)
Research and development tax credit		(1.51	)		(1.30	)
Acquisition costs		(0.91	)		—
Goodwill impairment		—			(0.22	)
Acquired in process research and development impairment		(7.03	)		—
Loss on warrant exchange and warrant FMV changes		0.03			(1.33	)
Permanent differences and other		(0.99	)		2.14
Change in valuation allowance		(12.49	)		(10.94	)
Effective tax rate		0.28	%		13.57	%

Deferred 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 and for tax carryforwards. Significant components of the Company’s deferred tax assets and liabilities are as follows:

	December 31,
	2019			2018
Deferred tax assets:
Domestic NOLs	$	8,141,204		$	4,025,587
Foreign NOLs		5,352,556			5,303,154
Accrued expenses		208,604			162,814
Amortization		947,115			1,035,765
Deferred revenue		44,558			38,494
Stock compensation		622,789			568,165
Deferred rent		—			336,070
Lease Liability		479,940			—
Research and development carryforward		73,155			73,156
Total deferred tax assets		15,869,921			11,543,205
Deferred tax liabilities:
IPR&D assets		(2,373,304	)		(2,557,085	)
Right of Use Asset		(192,160	)		—
Depreciation		(154,678	)		(205,859	)
IRC §481(a) adjustment		—			—
Total deferred tax liabilities		(2,720,142	)		(2,762,944	)
Deferred tax assets, net		13,149,779			8,780,261
Valuation allowance		(13,149,779	)		(8,838,761	)
Total deferred tax liabilities net	$	—		$	(58,500	)

The Company assesses the need for a valuation allowance against our deferred tax assets and considers both positive and negative evidence related to the likelihood of realization of the deferred tax assets to determine, based on the weight of available evidence, whether it is more-likely-than-not that some or all of the deferred tax assets will not be realized. This determination requires significant judgment, including assumptions about future taxable income that are based on historical and projected information. The increase in the valuation allowance during the year ended December 31, 2019 primarily relates to increases for current year losses in both the U.S. and foreign locations which the Company concluded needed a full valuation allowance. The Company has recorded a valuation allowance against its gross U.S. deferred tax assets it believes are not more likely than not realizable and the net non-U.S. deferred tax assets. Deferred tax liabilities, consist primarily of indefinite life IPR&D assets located in a foreign subsidiary, which will be applied in the future to offset against NOLs that have an unlimited life.

The Company has U.S. federal net operating loss carryforwards of approximately $29,596,042 as of December 31, 2019. Of this amount, $6,576,869 has a 20-year carry forward period that will expire at various dates beginning in 2021. Under current law, the remaining amount of $23,019,173 has an unlimited life.

As of December 31, 2019 and 2018, the Company does not have any material unrecognized tax benefits. The Company files income tax returns in the United States, various U.S. states, U.K., and France. The Company is still open to examination by the applicable taxing authorities from 2009 forward, although tax attributes that were generated prior to 2009 may still be adjusted upon examination by federal, state, foreign, or local tax authorities if they either have been or will be used in a future period. Under Section 382 of the Internal Revenue Code of 1986, as amended, substantial changes in the Company’s ownership may limit the amount of NOLs that can be utilized annually in the future to offset its U.S. federal and state taxable income. Specifically, this limitation may arise in the event of a cumulative change in ownership of the Company of more than 50% within any three-year period. The amount of the annual limitation is determined based on the value of the Company immediately before the ownership change. The Company has reduced the NOL and related valuation allowance in both 2018 and 2019 and subsequent ownership changes may further affect the limitation in future years.