U.S. GAAP requires the interim period tax provision to be determined as follows:

The estimated annual effective rate is applied to the year-to-date "ordinary" income at the end of each quarter to compute the year-to-date tax applicable to ordinary income. The tax expense or benefit related to ordinary income in each quarter is the difference between the most recent year-to-date and the prior quarter year-to-date computations.

The determination of the annual effective tax rate is based upon a number of significant estimates and judgments, including the estimated annual pretax income of the Company and the development of tax planning strategies during the year.

The following table includes tax expense and the effective tax rate for the Company's income from operations:

In 2010, the write-off of certain notes receivable was considered a capital loss for tax purposes. In assessing the realizability of this deferred tax asset, management determined that it was more-likely-than-not that all of this asset would not be realized and accordingly recorded a valuation allowance in the amount of $926. The valuation allowance for net deferred tax assets as of June 30, 2011 and December 31, 2010 was $3,444 for both periods and was related to capital losses of $2,157 and Federal and state net operating losses of $1,287 primarily due to Section 382 limitations. In assessing the realizability of deferred tax assets, management considers whether it is more-likely-than-not that some or all of the deferred tax assets will be realized.

Upon exercise of stock options, the Company recognizes any difference between U.S. GAAP compensation expense and income tax compensation expense as a tax windfall or shortfall. The difference is charged to equity in the case of a windfall. When the exercise results in a windfall and the windfall results in a net operating loss ("NOL"), or the windfall increases an NOL carryforward, no windfall is recognized until the deduction reduces the income tax payable. For U.S. GAAP purposes, the Company has deferred the recognition of approximately $1,408 in windfall tax benefits associated with its stock-based compensation until a cash tax savings is realized. The benefit will be recorded in stockholder's equity when utilized on an income tax return to reduce taxes payable, and as such, it will not impact the Company's effective tax rate.

The total amount of the gross liability for unrecognized tax benefits reported in other non-current liabilities was $744 and $612 at June 30, 2011 and December 31, 2010, respectively. At June 30, 2011, the amount of unrecognized tax benefits that would benefit the Company's effective tax rate, if recognized, was $557.

The Company recognizes potential interest and penalties related to unrecognized tax benefits in income tax expense. The Company had accrued interest and penalties of $195 as of both June 30, 2011 and December 31, 2010.

The Company files a consolidated federal income tax return and separate tax returns with various states. Additionally, a subsidiary of the Company files a tax return in a foreign jurisdiction. The Company's tax returns for the calendar years ended December 31, 2010 and 2009, and fiscal years ended March 31, 2009 and 2008 remain open to examination by the Internal Revenue Service in their entirety. They also remain open with respect to state taxing jurisdictions.