72 Pa. Stat. § 7256
Any party to a transaction who has paid tax by reason of a transaction with respect to which the department is assessing tax against another person may, within six months after the filing by the department of the assessment against such other person, file a special petition for refund, notwithstanding his failure to timely file a petition pursuant to section 3003.1 of Article XXX. The provisions of Article XXVII shall be applicable to such special petition for refund, except that the department need not act on such petition until there is a final determination as to the propriety of the assessment filed against the other party to the transaction. Where a petition is filed under this provision in order to take advantage of the extended period of limitations, overpayments by the petitioner shall be refunded but only to the extent of the actual tax (without consideration of interest and penalties) paid by the other party to the transaction. The purpose of this section is to avoid duplicate payment of tax where a determination is made by the department that one party to a transaction is subject to tax, and another party to the transaction has previously paid tax with respect to such transaction and, as such, this section shall be construed as extending right beyond that provided for by section 253 , and not to limit such other section.
72 P.S. § 7256