S.C. Code § 58-25-80
Each authority established, including any formed under Chapter 25 of Title 58 of the 1976 Code prior to the effective date of this chapter, exists for nonprofit and public purposes and is a public agency, and it is found and declared that the carrying out of the purpose of each authority is exclusively for public benefit and its property is public property. No authority shall pay any state or local ad valorem, income, sales, fuel, excise, or other use taxes or other taxes from which municipalities and counties are exempt. The South Carolina Department of Revenue is responsible for promulgating regulations necessary to effect fully this provision for tax exemption. The authority or operator providing public transportation on behalf of an authority may participate in the State Retirement System and utilize the services of the State Purchasing Department of the Division of General Services and any other joint activity of the State carried on for the benefit of state agencies and political subdivisions of the State. Operators providing public transportation on behalf of an authority shall not pay state and local fuel taxes from which municipalities and counties are exempt.
S.C. Code § 58-25-80