53 Pa. C.S. § 8426
(a) General rule.--All overpayments of tax due a local taxing authority, including taxes on real property, shall bear simple interest from the date of overpayment until the date of resolution.
(b) Interest rate.--Interest on overpayments shall be allowed and paid at the same rate as the Commonwealth is required to pay pursuant to section 806.1 of the act of April 9, 1929 (P.L. 343, No. 176), known as The Fiscal Code.
(c) Exceptions.--
(1) No interest shall be allowed if an overpayment is refunded or applied against any other tax, interest or penalty due the local taxing authority within 75 days after the last date prescribed for filing the report of the tax liability or within 75 days after the date the return or report of the liability due is filed, whichever is later.
(2) Overpayments of interest or penalty shall not bear any interest.
(d) Acceptance of refund check.--The taxpayer's acceptance of the local taxing authority's check shall not prejudice any right of the taxpayer to claim any additional overpayment and interest thereon. Tender of a refund check by the local taxing authority shall be deemed to be acceptance of the check by the taxpayer for purposes of this section.
(e) Definitions.--As used in this section, the following words and phrases shall have the meanings given to them in this subsection:
"Date of overpayment." The later of the date paid or the date tax is deemed to have been overpaid as follows:
(1) Any tax actually deducted and withheld at the source shall be deemed to have been overpaid on the last day for filing the report for the tax period, determined without regard to any extension of time for filing.
(2) Any amount overpaid as estimated tax for the tax period shall be deemed to have been overpaid on the last day for filing the final report for the tax period, determined without regard to any extension of time for filing.
(3) An overpayment made before the last day prescribed for payment shall be deemed to have been paid on the last day.
(4) Any amount claimed to be overpaid with respect to which a lawful administrative review or appellate procedure is initiated shall be deemed to have been overpaid 60 days following the date of initiation of the review or procedure.
(5) Any amount shown not to be due on an amended income or earned income and net profits tax return shall be deemed to have been overpaid 60 days following the date of filing of the amended income tax return.
"Date of resolution." The date the overpayment is refunded or credited as follows:
(1) For a cash refund, a date preceding the date of the local taxing authority's refund check by not more than 30 days.
(2) For a credit for an overpayment:
(i) the date of the local taxing authority's notice to the taxpayer of the determination of the credit; or
(ii) the due date for payment of the tax against which the credit is applied, whichever first occurs. For a cash refund of a previously determined credit, interest shall be paid on the amount of the credit from a date 90 days after the filing of a request to convert the credit to a cash refund to a date preceding the date of the refund check by not more than 30 days whether or not the refund check is accepted by the taxpayer after tender.
53 Pa.C.S. § 8426