S.C. Code § 59-71-510
For the payment of the principal and interest on all State school bonds at any time issued and outstanding pursuant to this article as now constituted or hereafter amended, there shall be pledged the full faith, credit and taxing power of the State and, in addition thereto, but subject to the provisions of Section 59-71-520, the entire amount of revenue derived from the retail sales tax levied by Chapter 35 of Title 12. The revenues derived from such retail sales tax during each fiscal year shall be discharged from the foregoing pledge when payment or provision for payment has been made for the principal and interest of all State school bonds maturing in such fiscal year and when the requirements of Section 59-71-570 as to payments into the sinking fund have been met.
S.C. Code § 59-71-510