Pennsylvania Statutes Title 24 P.S. Education § 582.8a. Review of returns; reassessment of taxes

No tax return shall be reexamined nor an additional tax imposed on any taxpayer on account of any rule or regulation which declares certain activities to be included in the retail business classification and which were allowed by the taxing authorities to be included in the wholesale business classification in previous returns, unless such rule or regulation is approved prior to the date such return is required to be filed.