For purposes of section 1181 of this title, any return filed before the last day prescribed for the filing thereof shall be considered as filed on such last day. For purposes of section 1181(b)(2) and (c) and section 1182 of this title, payment of any portion of the tax made before the last day prescribed for the payment of the tax shall be considered made on such last day. For purposes of this section, the last day prescribed for filing the return or paying the tax shall be determined without regard to any extension of time granted the taxpayer and without regard to any election to pay the tax in installments.