S.C. Code Ann. § 58-23-620: Situations in which local fees may or may not be imposed.

(A) A municipality or county in this State may not impose a license fee or license tax upon a holder of a certificate A or a certificate B, and a municipality or county may not impose a license fee or license tax on the holder of a certificate E or a certificate F, Certificate of Compliance, or a common or contract motor carrier of property, except the municipality of the carrier's residence or the location of the carrier's principal place of business. However, the fee required of a holder of a certificate C is in addition to any license tax or license fee charged by a municipality.

(B) If a municipality or county imposes a license fee or license tax pursuant to subsection (A), the fee or tax in the case of any certificate holder or common or contract motor carrier of property which operates its vehicles both within and without this State, must be apportioned in the ratio that the miles traveled by the vehicles operated by the certificate holder in this State bears to miles traveled by those vehicles in all states.