N.C. Gen. Stat. § 97-42

Payments made by the employer to the injured employee during the period of his disability, or to his dependents, which by the terms of this Article 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. Unless otherwise provided by the plan, when payments are made to an injured employee pursuant to an employer-funded salary continuation, disability or other income replacement plan, the deduction shall be calculated from payments made by the employer in each week during which compensation was due and payable, without any carry-forward or carry-back of credit for amounts paid in excess of the compensation rate in any given week.