S.C. Code Ann. § 9-12-40

All members, retired members, and beneficiaries of the retirement systems are eligible to participate in a QEBA if their benefits would exceed the limitation imposed by Section 415 of the Internal Revenue Code. Participation is determined for each calendar year, and participation shall cease for any calendar year in which the benefit of a member, retired member, or beneficiary is not limited by Section 415 of the Internal Revenue Code.