|12 Months Ended|
Dec. 31, 2018
|Income Tax Disclosure [Abstract]|
|Income Taxes||Income Taxes
The Tax Act was enacted on December 22, 2017 and includes a number of changes to existing tax laws that impact us, most notably it reduces the US federal corporate tax rate from 35% to 21%, for tax years beginning after December 31, 2017. The Tax Act made modifications to allowable tax depreciation, the deductability of compensation for officers, the deductibility of meals and entertainment expenses, and the deductibility of interest expense.
We remeasured our deferred tax assets and liabilities based on the impact of the federal tax rate change, recording a decrease to our net deferred tax asset balance and a corresponding increase to our income tax provision of approximately $0.6 million and $32.4 million for the year ended December 31, 2018 and 2017, respectively. We completed our accounting for the Tax Act during the fourth quarter of 2018.
The components of the income tax expense (benefit) for continuing operations are as follows (in thousands):
A reconciliation of income tax expense (benefit) from continuing operations to the amount computed by applying the statutory federal income tax rate to the net income (loss) from continuing operations is summarized as follows (in thousands):
We remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. Significant components of our deferred tax assets and liabilities as of December 31, 2018 and 2017 are shown below. We assess the positive and negative evidence to determine if sufficient future taxable income will be generated to use the existing deferred tax assets. Our evaluation of evidence resulted in management concluding that the majority of our deferred tax assets will be realized. However, we maintain a valuation allowance to offset certain net deferred tax assets as management believes realization of such assets are uncertain as of December 31, 2018, 2017 and 2016. The valuation allowance decreased $2.5 million in 2018, decreased $8.4 million in 2017 and increased $6.3 million in 2016.
As of December 31, 2018, we had federal net operating loss carryforwards set to expire through 2037 of $229.9 million and $125.3 million of state net operating loss carryforwards. We also have $23.0 million of federal research and development credit carryforwards, which expire through 2037. We have $22.7 million of California research and development credit carryforwards that have no expiration date.
Pursuant to Section 382 and 383 of the Internal Revenue Code of 1986, as amended, utilization of our net operating losses and credits may be subject to annual limitations in the event of any significant future changes in its ownership structure. These annual limitations may result in the expiration of net operating losses and credits prior to utilization. The deferred tax assets as of December 31, 2018 are net of any previous limitations due to Section 382 and 383.
We account for income taxes by evaluating a probability threshold that a tax position must meet before a financial statement benefit is recognized. The minimum threshold is a tax position that is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Our remaining liabilities for uncertain tax positions are presented net of the deferred tax asset balances on the accompanying consolidated balance sheet.
A reconciliation of the amount of unrecognized tax benefits at December 31, 2018, 2017 and 2016 is as follows (in thousands):
Included in the balance of unrecognized tax benefits at December 31, 2018 is $28.2 million of tax benefits that, if recognized would impact the effective rate. There are no positions for which it is reasonably possible that the uncertain tax benefit will significantly increase or decrease within twelve months.
We recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2018 and December 31, 2017, we recognized an immaterial amount of interest and penalties. We file income tax returns in the United States, various state jurisdictions, United Kingdom, and Canada with varying statutes of limitations. The federal statute of limitation remains open for the 2014 tax year to the present. The state income tax returns generally remain open for the 2013 tax year through the present. Net operating loss and research credit carryforwards arising prior to these years are also open to examination if and when utilized.
The IRS began an audit of our 2016 tax year during the quarter ended June 30, 2018. We believe our reserve for unrecognized tax benefits and contingent tax issues is adequate with respect to all open years. Notwithstanding the foregoing, we could adjust our provision for income taxes and contingent tax liability based on future developments.
The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef