72 Pa. Stat. § 3326
Such advance payment may be made on any tax to become due and payable on any report or reports to be filed during the calendar year one thousand nine hundred thirty-six for the calendar year one thousand nine hundred thirty-five or for any fiscal year beginning in the calendar year one thousand nine hundred thirty-five, except in the case of taxes on gross receipts from public utility business, in which case such advance payment may be made on reports to be filed on or before August first, one thousand nine hundred thirty-six, and February first, one thousand nine hundred thirty-seven, for the preceding six months ending June thirtieth, one thousand nine hundred thirty-six, and December thirty-first, one thousand nine hundred thirty-six, respectively.
72 P.S. § 3326