16 Pa. Stat. § 4709
At their annual budget session, the county commissioners shall make such an appropriation as will enable them to pay, and there shall be paid out of county taxes and county institution district taxes, a sum of money, each month, which shall be equal to the amount paid into the retirement fund by the county employes, less any sum of money required to be paid by an authority or any such other second class county entity, during the preceding month or bi-weekly pay periods in accordance with the provisions of section 1708: Provided, That an authority or any such other second class county entity operating in the county shall make such an appropriation as will enable either of them to separately pay, and there shall be paid out of each of their respective funds, a sum of money, each month, which shall be equal to the amount paid into the retirement fund by those employes who are employed by an authority and any such other second class county entity during the preceding monthly or bi-weekly pay periods in accordance with the provisions of section 1708.
The county commissioners shall appropriate such amounts as are certified by the State Employes' Retirement Board as necessary to establish reserves for the benefit of any former member of the county employes' retirement system, whose employment with the county was terminated because of the incorporation into the State highway system of all or any county highways, or sections thereof, bridges, tunnels, viaducts, or sections thereto, in counties of the second class, and who became a member of the State Employes' Retirement System and who elected to receive credit in the State Employes' Retirement System for service as a member of the county employes' retirement system. Such appropriations shall be made at the annual budget session next succeeding the year in which certification is received from the State Employes' Retirement System and payment to the State Employes' Retirement Fund shall be made within ninety (90) days of the adoption of the budget.
It shall be the duty of the county commissioners to appropriate annually sufficient funds, necessary to guarantee payment of all administrative costs, benefit commitments and legal obligations of the Employes' Retirement Board.
16 P.S. § 4709