S.C. Code Ann. § 9-1-420: Certain persons employed after December 31, 1948, are automatically members of system.

All persons who have or shall become teachers or employees after December 31, 1948, except those specifically excluded under Section 9-1-450 or those as to whom membership is optional under Sections 9-1-510 to 9-1-560, have become or shall become members of the System as a condition of their employment.