North Carolina General Statutes Chapter 66. Commerce and Business § 66-306. Late fees

(a) In all rental contracts in which a definite time for the payment of the rent is fixed, the late fee for each rental unit shall not exceed fifteen dollars ($15.00) or fifteen percent (15%) of the rental payment, whichever is greater, and shall not be imposed by the self-service storage business until the rental payment for that rental unit is five days or more late.

(b) A late fee under this section may be imposed only one time for each late rental payment. A late fee for a specific late rental payment shall not be deducted from a subsequent rental payment so as to cause the subsequent rental payment to be in default.