5.	Income Taxes

The Corporation’s effective income tax rate for the three months ended March 31, 2016 was 30.4%. The estimated effective income tax rates reflect the effect of federal and state income taxes and the impact of differences in book and tax accounting arising from the net permanent benefits associated with the statutory depletion deduction for mineral reserves and the domestic production deduction. For the three months ended March 31, 2015, there was an income tax benefit which reflects the exercise of converted stock awards issued to former TXI personnel.

The Corporation records interest accrued in relation to unrecognized tax benefits as income tax expense. Penalties, if incurred, are recorded as operating expenses in the consolidated statements of earnings and comprehensive earnings.