72 Pa. Stat. § 7272
The department or any of its authorized agents is hereby authorized to examine the books, papers and records of any taxpayer in order to verify the accuracy and completeness of any return made or, if no return was made, to ascertain and assess the tax imposed by this article. The department may require the preservation of all such books, papers and records for any period deemed proper by it but not to exceed three years from the end of the calendar year to which the records relate. Every such taxpayer is hereby required to give to the department, or its agent, the means, facilities and opportunity for such examinations and investigation. The department is further authorized to examine any person, under oath, concerning taxable sales or use by any taxpayer or concerning any other matter relating to the enforcement or administration of this article, and to this end may compel the production of books, papers and records and the attendance of all persons whether as parties or witnesses whom it believes to have knowledge of such matters. The procedure for such hearings or examinations shall be the same as that provided by The Fiscal Code relating to inquisitorial powers of fiscal officers.
72 P.S. § 7272