During the first quarter of 2008,three months ended March 31, 2009, our income tax benefit consistsexpense consisted of alternative minimum federal tax and state taxes and a tax benefit relating to the release of a portion of our deferred tax asset valuation allowance.income tax. Our effective income tax rate differs from the statutory income tax rate primarily as a result of the partial release of our valuation allowance for the future benefits to be received from our deferred tax assets as well as our use of federal net operating losses to offset current federal tax expense. A valuation allowance was originally recorded against our deferred tax assets as we determined the realization of these assets did not meet the more likely than not criteria in accordance with SFAS No. 109, “Accounting for Income Taxes”.Taxes.” During the first quarter of 2008, we determined that a full valuation allowance against our deferred tax assets was not necessary.necessary and recorded a partial reversal of deferred tax valuation allowance of $3.7 million. During the first quarter of 2009, we have re-evaluated our future operating income projections and determined that the realization of our net deferred tax asset continue to be more likely than not.  In making such determination we considered all available positive and negative evidence including our recent earnings trend and expected continued future taxable income.  During the first quarter of 2008, we recorded a partial reversal of deferred tax valuation allowance of $3.7 million primarily consisting of net operating loss carryforwards and research tax credits carryforwards. We continue to maintain a valuation allowance for the remainder of our deferred tax assets. WeIn September 2008 the State of California passed a legislation temporarily suspending the use of net operating losses to offset current state income tax expense. As a result of not being able to use our state NOLs, we incurred approximately $207,000 of additional California state income tax expense during the first quarter of 2009. During the three months ended March 31, 2009, we recorded a current tax provision for corporate alternative minimum federal taxes and state taxes of approximately $106,000 in the three months ended March 31, 2008. This resulted in an overall tax benefit of $3.6 million.$250,000.

We adopted the provisions ofUnder Financial Accounting Standards Board (FASB)(“FASB”) Interpretation No. 48, “Accounting for Uncertainty in Income Taxes, an interpretation of FASB Statement No. 109” (FIN 48) on January 1, 2007. Under FIN 48,, we are required to determine whether it is more likely than not that a tax position will be sustained upon examination based on the technical merits of the position.  A tax position that meets the more likely than not recognition threshold is measured to determine the amount of benefit to recognize in the financial statements. The adoption of FIN 48 did not have a material effect on our financial statements. We have concluded that there are no significant uncertain tax positions requiring recognition in our financial statements.

The following table summarizes our financial assets measured at fair value on a recurring basis in accordance with SFAS 157 (in thousands):

 

The fair value of our available-for-sale debt securitiesinvestments included in the Level 2 category is based on the market values obtained from an independent pricing service that were evaluated using pricing models that vary by asset class and may incorporate available trade, bid and other market information and price quotes from well established independent pricing vendors and broker-dealers.