72 Pa. Stat. § 702
If any corporation or association closes its fiscal year, not upon the thirty-first day of December, but upon some other date, and reports to the United States Government as of such other date, or would so report were it required to make a return to the United States Government, such corporation or association, except as otherwise provided in this section, shall certify such fact to the Department of Revenue and shall make any capital stock, franchise, or loans tax report or bonus report required to be made by it, or any of its officers, to the Department of Revenue, within one hundred five days after such date, subject in all other respects to the laws relating to the making of such reports and returns.
If any corporation or association on a fiscal period commonly referred to as a fifty-two-fifty-three week accounting fiscal basis closes its fiscal year upon one of the seven days of December or any one of the first seven days of January, and reports to the United States Government as of such date, or would so report were it to make a return to the United States Government, such corporation or association shall not be deemed to be on a fiscal year basis ending on such date but shall be deemed to be on a calendar year ending on December thirty-first.
The first report made by any corporation or association changing any return or report from the calendar to the fiscal year basis shall cover the period from the last day of the calendar year for which a return or report was filed to the first day of the fiscal year, and the Department of Revenue shall settle the tax for such intervening period at the proportionate annual rate provided by law, and also settle the bonus.
72 P.S. § 702