12.	Income Taxes

The provision for income taxes for interim periods is determined using an estimated annual effective tax rate as prescribed by ASC 740-270, Income Taxes, Interim Reporting. The effective tax rate may be subject to fluctuations during the year as new information is obtained, which may affect the assumptions used to estimate the annual effective tax rate, including factors such as valuation allowances and changes in valuation allowances against deferred tax assets, the recognition or de-recognition of tax benefits related to uncertain tax positions, if any, and changes in or the interpretation of tax laws in jurisdictions where BioTime conducts business. ASC 740-270 also states that if an entity is unable to reliably estimate a part of its ordinary income or loss, the income tax provision or benefit applicable to the item that cannot be estimated shall be reported in the interim period in which the item is reported.

For items that BioTime cannot reliably estimate on an annual basis (principally unrealized gains or losses generated on its Asterias and OncoCyte shares due to the changes in the respective stock prices of Asterias and OncoCyte), BioTime uses the actual year to date effective tax rate rather than an estimated annual effective tax rate to determine the tax effect of that item, including the use of all available net operating losses and other credits or deferred tax assets.

In connection with the deconsolidation of Asterias and OncoCyte (see Note 3), although neither deconsolidation was a taxable transaction to BioTime and did not create a current income tax payment obligation to BioTime, the market value of the respective shares BioTime holds creates a deferred tax liability to BioTime based on the closing price of the security, less the tax basis of the security BioTime has in such shares. The deferred tax liability generated by the Asterias and OncoCyte shares that BioTime holds as of September 30, 2017, is a source of future taxable income to BioTime, as prescribed by ASC 740-10-30-17, that will more likely than not result in the realization of its deferred tax assets to the extent of those deferred tax liabilities. This deferred tax liability is determined based on the closing price of those securities as of September 30, 2017. Due to the inherent unpredictability of future prices of these securities, BioTime cannot reliably estimate or project those deferred tax liabilities on an annual basis. Therefore, the deferred tax liability pertaining to Asterias and OncoCyte shares, determined based on the actual closing price on the interim period end date being reported on, and the related impacts to the valuation allowance and deferred tax asset changes, are recorded in the interim period in which they occur.

A valuation allowance is provided when it is more likely than not that some portion of the deferred tax assets will not be realized.

For federal income tax purposes, as a result of the deconsolidation of Asterias and OncoCyte as discussed in Note 3 and the deferred tax liabilities generated from the Asterias and OncoCyte share market values from their respective deconsolidation dates, including the changes to those deferred tax liabilities due to changes in the Asterias and OncoCyte stock price through September 30, 2017, BioTime's deferred tax liabilities exceeded its deferred tax assets by $4.8 million as of September 30, 2017. Accordingly, as of September 30, 2017, for federal income tax purposes, BioTime released its entire valuation allowance and recognized a federal deferred income tax expense of $4.8 million during the three and nine months ended September 30, 2017. For state income tax purposes, BioTime has a full valuation allowance on its state deferred tax assets as of September 30, 2017 and December 31, 2016 and, accordingly, no state tax provision or benefit was recorded for any period presented.

BioTime established a full valuation allowance as of December 31, 2016 and 2015 due to the uncertainty of realizing future tax benefits from its net operating loss carryforwards and other deferred tax assets. Accordingly, BioTime did not record any provision or benefit for income taxes for the three and nine months ended September 30, 2016.