S.C. Code Ann. § 50-5-305
(A) To be granted a resident commercial saltwater license authorized under this chapter:
(2) an applicant who did not file a South Carolina personal income tax form for the previous year must show documentation acceptable to the department proving the applicant was a resident of South Carolina for twelve consecutive months immediately prior to the date of application.
The applicant must also present an additional form of identification acceptable to the department.