S.C. Code Ann. § 9-1-1135

(A) Interest must be credited to the account of each member once each year as of June thirtieth, on the basis of the balance in the account of each member as of the previous June thirtieth. Upon the death, retirement, or termination of a member, interest must be figured to the end of the month immediately preceding the date of refund or retirement, interest being based on the balance in the member's account as of the June thirtieth immediately preceding the date of refund or retirement. (B) Notwithstanding subsection (A), interest must not be credited to an inactive member account. For purposes of this subsection, a member account becomes inactive on July first if no contributions were made to the account in the preceding twelve months.