No provision or benefit for federal or state income taxes has been recorded, as the Company has incurred a net loss for all of the periods presented, and the Company has provided a full valuation allowance against its deferred tax assets.

At December 31, 2016, and 2015, the Company had federal and Massachusetts net operating loss carryforwards of approximately $55,217,000 and $22,416,000, respectively, of which federal carryforwards will expire in varying amounts beginning in 2029. As of December 31, 2016 and 2015, approximately $1,432,000 and $762,000, respectively, of Federal and Massachusetts net operating loss carryforwards are from excess stock-based compensation, which are not included in the deferred tax asset as of December 31, 2016 and 2015. Massachusetts net operating losses began to expire in 2014. Utilization of net operating losses may be subject to substantial annual limitations due to the “change in ownership” provisions of the Internal Revenue Code, and similar state provisions. The annual limitations may result in the expiration of net operating losses before utilization. The Company has not yet conducted a study to determine if any such changes have occurred that could limit our ability to use the net operating losses and tax credit carryforwards. The Company also had research and development tax credit carryforwards at December 31, 2016 and 2015 of approximately $986,000 and $441,000, respectively.

Significant components of the Company’s net deferred tax asset are as follows:

The Company has maintained a full valuation allowance against its deferred tax assets in all periods presented. A valuation allowance is required to be recorded when it is more likely than not that some portion or all of the net deferred tax assets will not be realized. Since the Company cannot determine that it is more likely than not that it will generate taxable income, and thereby realize the net deferred tax assets, a full valuation allowance has been provided. The valuation allowance increased by $7,860,985 and $3,615,002 in 2016 and 2015, respectively, due to the increase in deferred tax assets, primarily due to net operating loss carryforwards. The Company has no uncertain tax positions at December 31, 2016 and 2015 that would affect its effective tax rate. The Company does not anticipate a significant change in the amount of uncertain tax positions over the next twelve months. Since the Company is in a loss carryforward position, the Company is generally subject to U.S. federal and state income tax examinations by tax authorities for all years for which a loss carryforward is available.

Income tax benefits computed using the federal statutory income tax rate differs from the Company’s effective tax rate primarily due to the following: