Selling, general and administrative expense for the three-month period ended February 28, 2013 increased $0.5 million from the prior year period.
Interest expense incurred for the three-month period ended February 28, 2013 was $17.4 million, of which $10.2 million was capitalized in connection with our Hunter, Texas cement plant expansion project and $7.2 million was expensed. Interest expense incurred for the three-month period ended February 29, 2012 was $17.0 million, of which $8.5 million was capitalized in connection with our Hunter, Texas cement plant expansion project and $8.5 million was expensed.
Income taxes for the interim periods ended February 28, 2013 and February 29, 2012 have been included in the accompanying financial statements on the basis of an estimated annual rate. The tax rate differs from the 35% federal statutory corporate rate primarily due to percentage depletion that is tax deductible, state income taxes and valuation allowances against deferred tax assets. The estimated annualized rate for continuing operations is 7.9% for fiscal year 2013 compared to 2.5% for fiscal year 2012. We made no income tax payments and received no refunds in the nine-month period ended February 28, 2013. We made income tax payments of $0.1 million, and received income tax refunds of less than $0.1 million in the nine-month period ended February 29, 2012.
Net deferred tax assets totaled $12.4 million at February 28, 2013 and $13.7 million at May 31, 2012, of which $9.7 million at February 28, 2013 and $10.7 million at May 31, 2012 were classified as current. Management reviews our deferred tax position and in particular our deferred tax assets whenever circumstances indicate that the assets may not be realized in the future and records a valuation allowance unless such deferred tax assets are deemed more likely than not to be recoverable. The ultimate realization of these deferred tax assets depends upon various factors including the generation of taxable income during future periods. The Company's deferred tax assets exceeded deferred tax liabilities as of February 28, 2013 and May 31, 2012 primarily as a result of recent losses. Management has concluded that the sources of taxable income we are permitted to consider do not assure the realization of the entire amount of our net deferred tax assets. Accordingly, a valuation allowance is required due to the uncertainty of realizing the deferred tax assets. We recorded a valuation allowance of $5.2 million in fiscal year 2012 through a charge to other comprehensive loss given the increase in actuarial losses in our retirement plans in 2012. We will continue to record additional valuation allowance against additions to our net deferred tax assets for fiscal year 2013 until Management believes it is more likely than not the deferred tax assets will be realized