No. But their records are subject to the law and must be made available as follows.
Local tax collectors are not considered "agencies" under the RTKL due to the Pennsylvania Local Tax Collection Law, 72 Pa. Cons. Stat. 5511.1-5511.42. 72 P.S. 5511.4c. entitled "Tax collection records" states as follows: "(c) This section shall not be construed to do any of the following: (1) Make a tax collector an "agency" or authorize requests of the tax collector for records pursuant to the act of June 21, 1957 (P.L. 390, No. 212), referred to as the Right-to-Know Law."
The Commonwealth Court in Current Status Inc. v. Hykel, 778 A.2d 781 (Pa. Cmwlth.) specifically addressed that question under the old RTKL concluding that local tax collectors are not subject to the RTKL. However, while the local tax collector is not itself an agency, the tax records that are maintained by that collector remain agency records, whether of the township, municipality or school district on whose behalf s/he collects.
In Hykel, the Commonwealth Court carefully explained that the records of tax collectors are public and can be obtained directly from governmental units that qualify as agencies under the RTKL, just not directly from the tax collector. The records are public and must be provided by the agency to the extent not otherwise protected from disclosure. The agencies have delegated the task of tax collection to the collectors, as a third party, and the records attendant to performing that governmental function cannot be shielded from view even though the tax collector is not itself an agency. It remains the agencys responsibility to respond to the requester and to furnish copies or perform redaction if needed for any non-public parts of the records.