The tax effects of significant temporary differences representing deferred tax assets at December 31, 2017 and 2016, are as follows:

The provision for income taxes is at an effective rate different from the federal statutory rate due principally to the following:

Income tax expense for the years ended December 31, 2017 and 2016 consists of the following:

The Company has recorded a valuation allowance to the full extent of its currently available net deferred tax assets which the Company determined to be not more-likely-than-not realizable. The Company has net operating loss carryforwards of approximately $15.0 million, which expire, if unused, between the years 2018 and 2036.

The Company may have been deemed to have experienced changes in ownership which may impose limitations on its ability to utilize net operating loss carryforwards under Section 382 of the Internal Revenue Code. However, as the deferred tax asset is fully offset by a valuation allowance, the Company has not yet conducted a Section 382 study to determine the extent of any such limitations.

The Company has analyzed its income tax positions using the criteria required by U.S. GAAP and concluded that as of December 31, 2017 and 2016, it has no material uncertain tax positions and no interest or penalties have been accrued. The Company has elected to recognize any estimated penalties and interest on its income tax liabilities as a component of its provision for income taxes.

The income tax returns of the Company for 2014, 2015, and 2016 are subject to examination by income taxing authorities, generally for three years after each was filed.