As regulatory guidance on combined reporting is still under review, no estimated tax payments on a combined reporting basis are due for December 15, 2011. Each entity must file an estimated tax payment on a separate entity basis for the final quarter. If, due to filing a combined report for the tax year beginning after December 31, 2010, the estimated tax payment does not meet the criteria set forth in the safe harbor provisions and would subject the entity to the underpayment of estimated tax penalty, the Office of Tax and Revenue will waive the penalty.