72 Pa. Stat. § 7361
Except as hereinafter provided this article shall take effect immediately, except the tax shall first apply and be imposed upon income received by or accrued to a taxpayer on and after June 1, 1971: Provided, however, That a taxpayer who filed returns on the basis of a fiscal year or who is the beneficiary of an estate or trust or member of a partnership which files its returns under this article on the basis of a fiscal year, shall be subject to tax for his first taxable period on the portion of his fiscal year or of the fiscal year of the estate, trust or partnership which postdates May 31, 1971, as prescribed by the department by regulations. Section 1016 which provides for additions or penalties to the tax shall not take effect until thirty days after the date on which the department has promulgated and issued regulations relating to the duties and liabilities imposed on taxpayers under this article.
72 P.S. § 7361