S.C. Code Regs. § § 114-4740
Every three years, if there is an assignment under part A of Title IV of the Social Security Act, or upon the request of either parent where an assignment exists under part D of Title IV of the Social Security Act, the Department of Social Services shall with respect to a support order being enforced under this part, taking into account the best interests of the child involved, review and, if appropriate, adjust the order in accordance with the guidelines if the amount of child support award under the order differs from the amount that would be awarded in accordance with the guidelines. Adjustments to support orders can only be done for those with assignments under part A of Title IV of the Social Security Act or part D of Title IV of the Social Security Act, and must be done pursuant to Article 5 of Chapter 17 of the South Carolina Children's Code.
S.C. Code Regs. § 114-4740