S.C. Code § 12-36-2680
The department shall prescribe an exemption certificate for use by persons purchasing items exempt pursuant to items (5), (6), (7), (16), (18), (32), and (44) of Section 12-36-2120. This exemption certificate may be presented upon each purchase by the holder, or the retailer may keep a copy of the certificate on file. When an exempt sale is made pursuant to a certificate on file, the purchaser must note on the purchase invoice the exempt items and state that the items are to be used for exempt purposes. When the purchase order meets the requirements of this section, the liability for any tax determined to be due is solely the purchaser's.
S.C. Code § 12-36-2680
2000 Act No. 399, Section 3.Z., provides, in pertinent part, as follows:
"This section takes effect upon approval by the Governor, or as otherwise stated, except that subsection C. applies to sales occurring after the date of approval by the Governor ...."