S.C. Code Ann. § 2-3-40

The clerk of the Senate shall, on the first day of each session, draw a pay certificate of fifteen dollars in favor of each Senator and the clerk of the House of Representatives shall likewise, on the first day of each session, draw a pay certificate of fifteen dollars in favor of each member of the House of Representatives, which shall be given in lieu of all postage to be used by such Senator or Representative in his official capacity during each session and shall be in addition to his per diem.