S.C. Code Ann. § 9-3-120

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 agent and the Secretary of the Department of Health, Education and Welfare of the United States shall agree upon, but, except as may be otherwise required by or under the Social Security Act as to the services to be covered, such agreement shall provide in effect that: (1) Benefits will be provided for employees 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 State will pay to the Secretary of the Treasury, at such time or times as may be prescribed under the Social Security Act, contributions with respect to wages as defined in Section 9-3-20 equal to the sum of the taxes which would be imposed by Sections 1400 and 1410 of the Federal Insurance Contributions Act if the services covered by the agreement constituted employment within the meaning of that act; (3) Such agreement shall be effective with respect to services in employment covered by the agreement performed after a date specified therein, except that such effective date may be made retroactive only to the extent permitted by the applicable provision of the Social Security Act; and (4) All services which constitute employment as defined in Section 9-3-20, are performed in the employ of the State or a political subdivision thereof, and are covered by a plan which is in conformity with the terms of the agreement and has been approved by the State agent under Section 9-3-130, shall be covered by the agreement.