Interest shall be credited to the account of each member once each year as of June 30, on the basis of the balance in the account of each member as of the previous June 30. Upon the death, retirement, or termination of a member, interest shall be figured to the end of the month immediately preceding the date of refund or retirement, interest being based on the balance in such member's account as of the June 30 immediately preceding the date of refund or retirement.
S.C. Code Regs. § 19-971