72 Pa. Stat. § 5020-304
Whenever an elected assessor, or, in townships of the first class, an assessor, assistant township assessor or assistant triennial assessor, refuses or neglects to qualify as required by law, or refuses or neglects to receive the precept and books for the triennial or other assessment, the county commissioners are hereby authorized to appoint a suitable person to serve as assessor on the eighth day after the time designated by this act to begin the assessment.
If the electors of any ward, borough, town or township shall fail to choose an assessor, or, in townships of the first class, an assistant township assessor or assistant triennial assessor, at the time appointed by law, or if any person elected to such office shall neglect or refuse to serve therein, or if any vacancy shall happen therein by death or otherwise, the commissioners of the county shall appoint a fit person to fill the office, who shall serve until the expiration of the then current term of such officer, and who shall have the same powers, be subject to the same penalties, and receive the same compensation, as if he had been elected to such office.
72 P.S. § 5020-304