S.C. Code Ann. § 9-1-1560

(A) Except as provided in subsection (E) of this section, upon retirement for disability on or after July 1, 1976, a Class One member shall receive a service retirement allowance if he has attained the age of sixty-five years. Otherwise he shall receive a disability retirement allowance which shall be computed as follows: (1) Such allowance shall be equal to the service retirement allowance which would have been payable had he continued in service to age sixty-five based on the average final compensation, minus the actuarial equivalent of the contribution the member would have made during such continued service, with an interest rate of four percent per annum. (2) Notwithstanding the foregoing provisions, any Class One member whose creditable service commenced prior to July 1, 1976, shall receive not less than the benefit which would have been provided by the provisions of this section in effect immediately prior to July 1, 1976. (B) Except as provided in subsection (E) of this section, upon retirement for disability on or after May 19, 1973, a Class Two member shall receive a service retirement allowance if he has attained the age of sixty-five years. Otherwise he shall receive a disability retirement allowance which shall be computed as follows: (1) Such allowance shall be equal to the service retirement allowance which would have been payable had he continued in service to age sixty-five based on the average final compensation, minus the actuarial equivalent of the contribution the member would have made during such continued service, with an interest rate of four percent per annum. (2) Notwithstanding the foregoing provisions, any Class Two member whose creditable service commenced prior to July 1, 1964, shall receive not less than the benefit provided by subsection (A) of this section. (C) Except as provided in subsection (E) of this section, employees retired on disability subsequent to July 1, 1982, must have their benefits recalculated in accordance with the provisions of item (1) of subsection (A) and item (2) of subsection (B). (D) Notwithstanding any other provision of this section, upon retirement for disability after October 15, 1992, at any age, a member must receive a disability retirement allowance equal to at least fifteen percent of his average final compensation. (E)(1) Upon retirement for disability based on an application for disability benefits received by the system after December 31, 2013, a Class One member shall receive a disability retirement allowance equal to one and forty-five hundredths percent of his average final compensation multiplied by the number of years of his creditable service as of the date of retirement, without reduction because of commencement before the normal retirement date. (2) Upon retirement for disability based on an application for disability benefits received by the system after December 31, 2013, a Class Two or Class Three member shall receive a disability retirement allowance equal to one and eighty-two hundredths percent of his average final compensation, multiplied by the number of years of his creditable service as of the date of retirement, without reduction because of commencement before the normal retirement date.