Income tax expense is comprised of the following:

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 tax purposes.  The following table sets forth the significant components of our net deferred tax asset and liability as of December 31, 2017 and 2016:

 

In December 2017, we recorded $5.0 million of tax expense necessary to revalue our deferred tax assets and liabilities at the new 21% federal rate as enacted in the Tax Cuts and Jobs Act of 2017 (the "Tax Act").

At December 31, 2017, we provided valuation allowances for $3.4 million of deferred tax assets associated with our international net operating loss carryforwards and $8.1 million for deferred tax assets related to capital loss carryforwards incurred in the sale of the TPHS business.  We recorded a total decrease in our valuation allowance of $3.7 million for the year ended December 31, 2017, which included a $4.0 million decrease recorded to continuing operations related to the change in federal tax rate from 35% to 21% under the Tax Act for deferred tax assets subject to valuation allowance.  The remaining $0.3 million offsetting increase in valuation allowance for 2017 related to international net operating loss and capital loss carryforwards and was recorded to discontinued operations.  Our valuation allowance at December 31, 2017 is $11.5 million.

At December 31, 2017, we had international net operating loss carryforwards totaling approximately $12.9 million with an indefinite carryforward period, approximately $99.2 million of federal net operating loss carryforwards, approximately $151.9 million of state net operating loss carryforwards expiring between 2018 and 2036, approximately $30.5 million of capital loss carryforwards expiring in 2021, and approximately $4.6 million of foreign tax credits expiring between 2022 and 2027. Of the federal net operating loss carryforwards, $2.8 million is subject to annual limitation under Internal Revenue Code Section 382 and expires in 2021, if not utilized. The remainder of the federal net operating loss carryforwards expire between 2035 and 2036.

Upon adoption of ASU 2016-09 on January 1, 2017, we recorded a $6.5 million increase in deferred tax assets as a cumulative-effect adjustment to retained earnings.  The increase in deferred tax assets related to the previously suspended portion of net operating losses attributable to excess tax deductions from share-based payment awards.  In 2016, pursuant to ASC Topic 718-740, "Stock Compensation", we tracked in a separate memo account the portion of our cumulative net operating losses attributable to excess tax deductions from share-based payment awards, which totaled $16.5 million at December 31, 2016. The tax benefits related to these amounts were not included in our gross or net deferred tax assets and were not recorded to additional paid-in capital at December 31, 2016 since the related tax deduction would not have reduced cash taxes payable.

In 2017, our undistributed foreign earnings were subject to the mandatory deemed repatriation ("toll charge") provision included in the Tax Act, and we repatriated these earnings during 2017.  Due to the mandatory deemed repatriation, we recorded $2.5 million of tax expense in continuing operations as of the date of enactment.  We have no undistributed earnings at December 31, 2017.  We recorded a $1.6 million deferred tax liability on $13.9 million of undistributed foreign earnings at December 31, 2016.

The difference between income tax expense computed using the statutory federal income tax rate and the effective rate is as follows:

 

Uncertain Tax Positions

As of December 31, 2017, we had $0.6 million of unrecognized tax benefits that, if recognized, would affect our effective tax rate. Our policy is to include interest and penalties related to unrecognized tax benefits in income tax expense. During 2017 and 2016, there were no interest and penalties related to unrecognized tax benefits recorded as income tax expense. During 2015, we included an immaterial amount of net interest related to uncertain tax positions as a component of income tax expense.

The aggregate changes in the balance of unrecognized tax benefits, exclusive of interest, were as follows:

 

We file income tax returns in the U.S. Federal jurisdiction and in various state and foreign jurisdictions.  Tax years remaining subject to examination in the U.S. Federal jurisdiction include 2014 to present.