S.C. Code Ann. § 12-28-945
Each licensed tank wagon operator-importer who is liable for the tax imposed by this chapter on nonexempt motor fuel imported by a tank wagon as to which tax previously has not been paid to a supplier, shall remit the taxable motor fuel tax for the preceding month's import activities with his monthly report of activities. A licensed tank wagon importer is allowed to retain the tare allowance provided for in Section 12-28-960(A).