(a) Federal-State Agreement.--The State Agency, which the approval of the Governor, is hereby authorized to enter on behalf of the Commonwealth into an agreement with the Federal Secretary of Health, Education and Welfare, consistent with the terms and provisions of this act, for the purpose of extending the benefits of the Federal old-age and survivors insurance system to employes of the Commonwealth or any political subdivision or instrumentality thereof, with respect to services specified in such agreement which constitute "employment" as defined in section two of this act. Such agreement may contain such provisions relating to coverage, benefits, contributions, effective date, modification and termination of the agreement, administration, and other appropriate provisions, as the State Agency and Federal Secretary of Health, Education and Welfare shall agree upon, but, except as may be otherwise required by or under the Social Security Act as to the service to be covered, such agreement shall provide in effect that-- (1) Benefits will be provided for employes whose services are covered by the agreement and their dependents and survivors on the same basis as though such services constituted employment within the meaning of Title II of the Social Security Act; (2) The Commonwealth will pay to the Federal Agency, at such time or times as prescribed by the applicable Federal law and by regulations promulgated thereunder, contributions with respect to wages (as defined in section two of this act), not in excess of the sum of taxes on employes and taxes on employers prescribed under the provisions of the Federal Insurance Contributions Act. The actual amount of the contributions to be made under the provisions of this clause shall be the amount necessary to carry out the provisions of this act and the agreement entered into in accordance therewith, which amounts shall, from time to time, be determined by the State Agency, subject to the limitations herein prescribed.(3) Such agreement shall be effective with respect to services, in employment covered by the agreement, performed on and after the first day of January, one thousand nine hundred fifty-one, or such later date as may be specified in the agreement, and modifications may be made effective subject to the limitations imposed by Federal law;(4) All services which constitute employment, as defined in section two, and are performed in the employ of the Commonwealth by employes of the Commonwealth, shall be covered by the agreement, except that it may exclude services which are optionally excludable under the Federal Social Security Act;(5) All services which constitute employment, as defined in section two, and are performed in the employ of a political subdivision or instrumentality thereof, and are covered by a plan which is in conformity with the terms of the agreement and has been approved by the State Agency under section six, shall be covered by the agreement;(6) As modified, the agreement may include all services described in clause (4) or clause (5) of this subsection and performed by individuals to whom section 218(c)(3)(C) of the Social Security Act is applicable, and shall provide that the service of the individual shall continue to be covered by the agreement in case he thereafter becomes eligible to be a member of a retirement system; and(7) As modified, the agreement shall include all services described in clause (4) or clause (5) of this subsection and performed by individuals in positions covered by a retirement system with respect to which the Governor has issued a certificate to the Federal Secretary of Health, Education and Welfare, pursuant to section 6.1 of this act. (b) Interstate Instrumentalities.--Any instrumentality jointly created by this Commonwealth and any other state or states is hereby authorized, upon the granting or existence of like authority by such other state or states, (1) to enter into an agreement with the Federal Secretary of Health, Education and Welfare whereby the benefits of the Federal old-age and survivors insurance system shall be extended to employes of such instrumentality, (2) to require its employes to pay, and for that purpose to deduct from their wages, contributions equal to the amounts which they would be required to pay under section five (a) if they were covered by an agreement made pursuant to subsection (a) of this section, and (3) to make payments to the Federal agency in accordance with such agreement, including payments from its own funds and otherwise, to comply with such agreement.1952, Jan. 5, P.L. (1951) 1833, § 4; 1956, June 1, P.L. (1955) 1973, § 1; 1957, July 8, P.L. 550, § 1.