N.C. Gen. Stat. § 64-36

A determination by the Commissioner pursuant to this Article shall be final, unless within 15 days after receipt of notice thereof by certified mail with return receipt, by signature confirmation as provided by the U.S. Postal Service, by a designated delivery service authorized pursuant to 26 U.S.C. § 7502(f)(2) with delivery receipt, or via hand delivery, the employer charged with the violation takes exception to the determination, in which event final determination shall be made in an administrative proceeding pursuant to Article 3 of Chapter 150B of the General Statutes and in a judicial proceeding pursuant to Article 4 of Chapter 150B of the General Statutes.