53 Pa. Stat. § 13438
The city, county, or other public employes, if any, herein mentioned, shall, after the passage of this act, pay unto the board of pensions, monthly, an amount equal to two per centum of their monthly salaries or wages,--in no event, however, except as herein provided, shall such employe be required to pay at a rate greater than four dollars a month,--which shall be applied to the purposes of this act. Whenever two per centum of the monthly salary or wages of any such employe shall exceed the sum of four dollars a month, then such employe, shall pay unto the board of pensions four per centum of the portion of his or her salary, or other compensation, which is over and above the amount of salary, or other compensation, which is sufficient to require the monthly payment of four dollars a month at the rate of two per centum of such salary, or other compensation, and he or she shall thereafter be required to pay such increased monthly rate without regard to the limit of four dollars a month: Provided, That such additional monthly payments shall not exceed eight dollars a month and the total monthly payment shall not exceed twelve dollars a month. Payment of the monthly amount or contribution herein mentioned shall cease and be discontinued at the time the beneficiary receives the pension herein provided, if such beneficiary has so contributed to the pension fund during a period of twenty years. If, at the time the beneficiary receives the pension herein provided, he or she shall not have been a contributor to the pension fund during a period of twenty years, such persons shall be required to pay unto the board of pensions an amount equal to four per centum of his or her monthly pension until such time as his or her contribution shall have extended during a period of twenty years. If, for any cause, an employe contributing to the pension fund shall cease to be an employe of any such cities of the first class, or other county or public employes paid out of the treasury of such cities, before said employe becomes entitled to the pension conferred by this act, the total amount of the contributions paid into the pension fund by such employe shall be refunded to him in full, without interest: Provided, however, If any such employe shall have returned to him or her the amount contributed, as aforesaid, and shall afterward re-enter such public employment, said employe shall not be entitled to the pension designated until twenty years after the said reemployment, unless he or she shall return to the pension fund the amount withdrawn; in which event the period of twenty years shall be computed from the time said employe first entered the said public service. In the event of the death of any employe before the said employe becomes entitled to the pension aforesaid, the said total amount of contributions aforesaid shall be paid over to the estate of said deceased employe.
53 P.S. § 13438