S.C. Code Ann. § 57-11-270: Revision of taxes included in sources of revenue.

The pledge of monies derived from the sources of revenue shall not preclude the General Assembly from revising the quantum of any tax included in the sources of revenue except that, so long as any state highway bonds shall be outstanding, the sources of revenue shall be not less than the amount needed to fund the general operations budget of the department and debt service requirements for annual principal and interest payments on state highway bonds.