We file a consolidated federal income tax return for all of our wholly-owned subsidiaries, including Sirius XM.  Income tax expense for the three months ended June 30, 2015 and 2014 was $45,421 and $86,822, respectively, and $184,350 and $163,570, respectively, for the six months ended June 30, 2015 and 2014.  We estimate our annual effective tax rate for the year ending December 31, 2015 will be 38.3%. Our effective tax rate for the three and six months ended 2015 was 30.6% and 46.9%, respectively, primarily due to the effect of a tax law change in the District of Columbia during the three months ended March 31, 2015 and in New York City during the three months ended June 30, 2015.  The tax law change in the District of Columbia will reduce our future taxes and thus we will use less of certain net operating losses in the future which resulted in a $44,392 increase in our valuation allowance during the three months ended March 31, 2015.  The tax law change in New York City will increase certain net operating losses to be utilized in the future resulting in a $16,945 increase in our deferred tax asset during the three months ended June 30, 2015.  Our effective tax rate for the six months ended June 30, 2014 was 43.3% due to the impact of the loss on change in fair value of the derivative related to the share repurchase agreement with Liberty Media.

As of June 30, 2015 and December 31, 2014, we had a valuation allowance related to deferred tax assets of $49,387 and $4,995, respectively, that were not likely to be realized due to certain state net operating loss limitations and acquired net operating losses that we were not likely to utilize.