14. Income Taxes

In accordance with the authoritative guidance for income taxes under ASC 740, a deferred tax asset or liability is determined based on the difference between the financial statement and the tax basis of assets and liabilities as measured by the enacted tax rates, which will be in effect when these differences reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized.

The Company recognizes the impact of a tax position in the financial statements only if that position is more likely than not of being sustained upon examination by taxing authorities, based on the technical merits of the position. The Company’s practice is to recognize interest and/or penalties related to income tax matters in income tax expense.

The Company is subject to taxation in the U.S. and various state jurisdictions. Currently no years are under examination. All tax years are subject to examination by the U.S. and state tax authorities due to the carry-forward of unutilized net operating losses and research and development credits.

A reconciliation of income tax expense (benefit) for the years ended December 31, 2016, 2015, and 2014 is as follows:

Significant components of the Company’s deferred income taxes at December 31, 2016 and 2015 are shown below (in thousands):

The Company has established a valuation allowance against net deferred tax assets due to the uncertainty that such assets will be realized. The Company periodically evaluates the recoverability of the deferred tax assets. At such time as it is determined that it is more likely than not that deferred tax assets will be realizable, the valuation allowance will be reduced. The Company has not considered the deferred tax liability related to acquired in-process research and development to be a future source of taxable income in evaluating the need for a valuation allowance against its deferred tax assets due to the in-process research and development asset being considered an indefinite-lived intangible asset.

At December 31, 2016, the Company had federal and California net operating losses, or NOL, carryforwards of approximately $54.0 million and $47.0 million, respectively. The federal NOL carryforwards begin to expire in 2027, and the California NOL carryforwards begin to expire in 2029. At December 31, 2016, the Company also had federal and California research tax credit carryforwards of approximately $1.2 million and $0.3 million, respectively. The federal research tax credit carryforwards begin to expire in 2029, and the California research tax credit carryforwards do not expire and can be carried forward indefinitely until utilized.

The above NOL carryforwards and the research tax credit carryforwards may be subject to an annual limitation under Section 382 and 383 of the Internal Revenue Code of 1986, and similar state provisions if the Company experienced one or more ownership changes, which would limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382 and 383, results from transactions increasing ownership of certain stockholders or public groups in the stock of the corporation by more than 50 percentage points over a three-year period. The Company has not completed an IRC Section 382/383 analysis. If a change in ownership were to have occurred, NOL and tax credit carryforwards could be eliminated or restricted. If eliminated, the related asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance. As long as the Company maintains a full valuation allowance against its deferred tax assets, limitations created by future ownership changes, if any, will not impact the Company’s effective tax rate.

A reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows: