S.C. Code Ann. § 38-21-130
Every insurer authorized to do business in this State which is a member of an insurance holding company system shall register with the department, except a foreign insurer subject to registration requirements and standards adopted by statute or regulation in the jurisdiction of its domicile which are substantially similar to those contained in this chapter.
Any insurer which is subject to registration under this chapter shall register within fifteen days after it becomes subject to registration, and annually thereafter by March first of each year for the previous calendar year, unless the director or his designee for good cause shown extends the time for registration, and then within the extended time. The director or his designee may require any authorized insurer which is a member of a holding company system which is not subject to registration under this section to furnish a copy of the registration statement or other information filed by the insurance company with the insurance regulatory authority of its domiciliary jurisdiction.