53 Pa. Stat. § 15324
In the month of November, the Department of Health shall send to the shop of each licensed master plumber, possessing a certificate of that year, an application for a certificate for the succeeding year, and those desiring to continue in the trade of plumbing may, either deliver in person, or mail into the Department of Health the said application, properly executed and signed, together with the fee prescribed hereinafter, not later than the thirty-first day of December, and the Department of Health shall then mail the certificate to the licensed master plumber, certifying him as a licensed registered master plumber. The cost of securing such certificate each year shall be three dollars ($3.00), and no other cost to be imposed by the city.
Upon the failure of a licensed master plumber to make proper application for his certificate, as herein provided, by the thirty-first day of December, he shall pay a penalty of two dollars ($2.00), and those licensed master plumbers, who fail to secure a certificate for two years, shall take an examination as required of applicants by this act.
53 P.S. § 15324