S.C. Code Ann. § 29-6-270: Credit rating of state in which surety company licensed.

For any contract for the improvement of real property not covered by the provisions of Section 29-6-250, where a payment bond is required by the contract or otherwise, the bond may only be issued by a surety company licensed in the State with a "B+" minimum rating as stated in the most current publication of "Best Key Rating Guide, Property Liability".