S.C. Code Ann. § 48-3-120

The bonds authorized by this chapter and the income therefrom, all trust indentures and mortgages executed as security therefor, all lease agreements made pursuant to the provisions hereof, and the revenues derived from any loan agreement thereof shall be exempt from all taxation in the State of South Carolina except for inheritance, estate or transfer taxes; and all trust indentures, mortgages and loan agreements made pursuant to the provisions of this chapter shall be exempt from South Carolina stamp and transfer taxes.