7. INCOME TAXES
The tax effects of temporary differences and carryforwards that give rise to significant portions of deferred assets and liabilities consist of the following (in thousands):
| December 31, | ||||||||
| 2016 | 2015 | |||||||
| Deferred tax assets: | ||||||||
| Deferred settlement costs | $ | 180 | $ | 492 | ||||
| Stock-based compensation | 674 | 543 | ||||||
| Accrued liabilities and other | 509 | 516 | ||||||
| Net operating loss carryforwards and credits | 68,186 | 67,350 | ||||||
| Total deferred tax assets | 69,549 | 68,901 | ||||||
| Less: valuation allowance | (69,528 | ) | (68,891 | ) | ||||
| Deferred tax assets, net of valuation allowance | 21 | 10 | ||||||
| Deferred tax liabilities: | ||||||||
| Depreciation and amortization | (21 | ) | (10 | ) | ||||
| Net deferred tax liability | $ | - | $ | - | ||||
A reconciliation of the federal statutory income tax rate and the effective income tax rate is as follows:
| December 31, | ||||||||
| 2016 | 2015 | |||||||
| Statutory federal tax rate | (34% | ) | (34% | ) | ||||
| Impact on state tax rates | (2% | ) | (2% | ) | ||||
| Stock compensation | 3% | 0% | ||||||
| Valuation allowance | 32% | 34% | ||||||
| Other non deductible permanent items | 1% | 2% | ||||||
| 0% | 0% | |||||||
At December 31, 2016 and 2015, we had net deferred tax assets totaling approximately $69.5 million and $68.9 million, respectively. These assets are offset by valuation allowances due to our determination that the criteria for asset recognition have not been met, as well as by deferred tax liabilities. At December 31, 2016, we had federal net operating loss carryforwards of approximately $180 million, which begin to expire in 2017 through 2035. In addition, we have tax credit carryforwards of approximately $5.2 million. Utilization of net operating loss carryforwards and tax credit carryforwards are subject to the “change of ownership” provisions under Section 382 of the Internal Revenue Code. The amount of such limitations has not been determined. Also, given that our net operating losses have yet to be utilized, all previous tax years remain open to examination by Federal authorities and other jurisdictions in which we operate. We have no unrecognized tax benefits as of December 31, 2016 and 2015.