S.C. Code § 41-27-265
2015 Act No. 77, Section 3, provides as follows:
"SECTION 3. This act takes effect upon approval by the Governor. The provisions contained in SECTION 1 shall retroactively apply to contribution rates calculated and imposed on or after January 1, 2015. Where the application of SECTION 1 would result in the reduction of contribution rates on an employer, the department shall credit that amount against future contributions from that employer until the credit is exhausted."