53 Pa. Stat. § 30555
There is hereby created in each city of the second class A, in which a retirement system has been established under this act, a city employes' retirement fund which shall consist of all moneys arising from appropriations made by the city and from contributions made by the members of the city employes' retirement system and all interest earned by the investments or moneys of the fund created by this act. The moneys contributed by the city shall be credited to a city annuity reserve account and those contributed by the members shall be credited to a member's annuity reserve account. Upon the granting of a retirement allowance to any contributor, whether as a superannuation retirement allowance, an involuntary retirement allowance or a total disability retirement allowance, as hereinafter provided, the amount of such contributor's accumulated deductions in the members' annuity reserve account shall lose their status as accumulated contributions and shall be transferred to a retired members' reserve account, and the actuarial equivalent of the city annuity shall be similarly transferred from the city annuity reserve account to the retired members' reserve account. The interest earnings shall be apportioned to the members' annuity and city annuity and retired members' reserve accounts. The actuary shall determine the present value of the liability on account of all city annuities payable to original members and the percentage of such liability which shall be contributed by the city each year over a period of fifteen years from the time the system is established until the accumulated reserve equals the present value of said liability. All such contributions shall be credited to the city annuity reserve account. The actuary shall also determine the amount which shall be contributed by the city into the fund periodically for credit to the city annuity reserve account on account of service of all new and original members subsequent to the time the retirement system is established.
Each member of the retirement system shall be required to contribute to the fund such per centum of his salary, as shall be computed by the actuary, to be sufficient, with regular interest, to procure for him on superannuation retirement one one-hundred-twentieth of his final salary for each year of service after December thirty-first preceding the year the retirement system is established, which contributions shall be paid into the fund through payroll deductions in such manner as the board may require. All contributions by members shall be credited to the member's annuity reserve account.
The board may, at any time, by rule, authorize members of the retirement system, whether original or new members, to transfer from the one one-hundred-twentieth class or from the one one-hundredth class to the one-eightieth class, and whenever such transfer shall be authorized, salary deductions applicable to such transferred members shall be based upon the same age of the contributor as was used in determining the per centum of salary deduction applicable while in the one one-hundred-twentieth class or the one one-hundredth class, as the case may be.
53 P.S. § 30555