53 Pa. C.S. § 8422
The following words and phrases when used in this subchapter shall have the meanings given to them in this section unless the context clearly indicates otherwise:
"Assessment." The determination by a local taxing authority of the amount of underpayment by a taxpayer.
"Board." A board of local tax appeals established under section 8430 (relating to administrative appeals).
"Eligible tax." Any of the following, including interest and penalty provided by law, when levied by a political subdivision:
(1) Any tax authorized or permitted under the act of December 31, 1965 (P.L. 1257, No. 511), known as The Local Tax Enabling Act.
(2) Any per capita tax levied under any act.
(3) Any occupation, occupation assessment or occupation privilege tax levied under any act.
(4) Any tax on income levied under any act.
(5) Any tax measured by gross receipts levied under any act.
(6) Any tax on a privilege levied under any act.
(7) Any tax on amusements or admissions levied under any act.
(8) Any tax on earned income and net profits.
"Governing body." A city council, borough council, incorporated town council, board of township commissioners, board of township supervisors, a governing council of a home rule municipality or optional plan municipality, a governing council of any similar general purpose unit of government which may hereafter be created by statute or a board of school directors of a school district.
"Local taxing authority." A political subdivision levying an eligible tax. The term shall include any officer, agent, agency, clerk, income tax officer, collector, employee or other person to whom the governing body has assigned responsibility for the audit, assessment, determination or administration of an eligible tax. The term shall not include a tax collector or collection agency who has no authority to audit a taxpayer or determine the amount of an eligible tax or whose only responsibility is to collect an eligible tax on behalf of the governing body.
"Overpayment." Any payment of tax which is determined in the manner provided by law not to be legally due.
"Taxpayer." An individual, partnership, association, corporation, limited liability company, estate, trust, trustee, fiduciary or any other entity subject to or claiming exemption from any eligible tax or under a duty to perform an act for itself or for another under or pursuant to the authority of an act providing for an eligible tax.
"Underpayment." The amount or portion of any tax determined to be legally due in the manner provided by law for which payment or remittance has not been made.
"Voluntary payment." A payment of an eligible tax made pursuant to the free will of the taxpayer. The term does not include a payment made as a result of distraint or levy or pursuant to a legal proceeding in which the local taxing authority is seeking to collect its delinquent taxes or file a claim therefor.
53 Pa.C.S. § 8422