S.C. Code Ann. § 5-21-790

All moneys derived from the collection of the assessments upon which any such paving bonds are predicated, which are collected subsequent to the passage of the ordinance authorizing the bonds, including all interest on any deferred payment of the assessments, shall be placed in a special fund to be used only for the payment of the principal and interest of the bonds. The amount of such special fund to be applied to the payment of interest shall not exceed so much of such fund as shall have been derived from the collections by way of interest on deferred payments of the assessments. The special fund shall be pledged for such purposes and such pledge shall be an obligation of the contract between the municipality and the holders of its paving bonds.