S.C. Code Regs. § § 117-304.1
An agency of the State of South Carolina is not deemed to be selling tangible personal property at retail when transferring tangible personal property to another agency of the State or to a county or to a municipality if the consideration for the transfer only reimburses the transferring agency for its cost and expenses in conveying the property; provided transferring agency has paid tax on the initial purchase of the tangible personal property. In addition, the provisions of Code Section 12-36-910(B)(4) do not apply to a State agency that manufactures tangible personal property within the State and uses or consumes the property in the State if the State agency paid tax on the cost of the tangible personal property incorporated into the item the agency manufactured for its own use or consumption.
Where, however, a State agency sells tangible personal property to persons other than another State agency, county, or municipality for use or consumption, such sales shall be considered retail sales subject to the tax. The agency making the sale is required to be licensed as a retailer under the terms and provisions of the sales and use tax law.
S.C. Code Regs. § 117-304.1