S.C. Code Ann. § 42-9-210: Deduction from compensation of payments made by employer when not due and payable.

Any payments made by an employer to an injured employee during the period of his disability, or to his dependents, which by the terms of this title were not due and payable when made may, subject to the approval of the commission, be deducted from the amount to be paid as compensation; provided, that in the case of disability such deductions shall be made by shortening the period during which compensation must be paid and not by reducing the amount of the weekly payment.