Section 7326 - Payments of estimated tax(a) Subject to the provisions of subsection (j) of section 325, the estimated tax with respect to which a declaration is required shall be paid as follows: (1) If the declaration is filed on or before April 15 of the taxable year, the estimated tax shall be paid in four equal installments. The first installment shall be paid at the time of the filing of the declaration, and the second, third and fourth installments shall be paid on or before the succeeding June 15, September 15, and January 15, respectively.(2) If the declaration is not required to be filed on or before April 15 of the taxable year and is filed after April 15, but before June 16 of the taxable year, the estimated tax shall be paid in three equal installments. The first installment shall be paid at the time of the filing of the declaration, and the second and third installments shall be paid on the succeeding September 15 and January 15, respectively.(3) If the declaration is not required to be filed on or before June 15 of the taxable year and is filed after June 15 but before September 16 of the taxable year, the estimated tax shall be paid in two equal installments. The first installment shall be paid at the time of the filing of the declaration, and the second shall be paid on the succeeding January 15.(4) If the declaration is not required to be filed on or before September 15 of the taxable year and is filed after September 15 of the taxable year, the estimated tax shall be paid in full at the time of the filing of the declaration.(5) If the declaration is not filed within the time prescribed therefor, or after the expiration of any extension of time therefor, clauses (2), (3) and (4) of this subsection shall not apply, and there shall be paid at the time of such filing the amount of all installments of estimated tax which were due and payable on or before the date the declaration was filed, and the remaining installments shall be paid at such times and in such amounts as they would have been payable if the declaration had been filed when due.(b) If an individual described in subsection (e) of section 325 (relating to farmers) makes a declaration of estimated tax after September 15 of the taxable year, but before the following March 1, the estimated tax shall be paid in full at the time of the filing of the declaration.(c) If any amendment of a declaration is filed, the remaining unpaid installments, if any, shall be ratably increased or decreased, as the case may be, to reflect any increase or decrease in the estimated tax by reason of such amendment, and if any amendment is made after September 15 of the taxable year, any increase in the estimated tax by reason thereof shall be paid at the time of making such amendment.1971, March 4, P.L. 6, No. 2, art. III, § 326, added 1971, Aug. 31, P.L. 362, No. 93, § 4.