S.C. Code § 38-71-780
A group hospital or medical expense insurance policy, hospital service plan contract, or medical service plan contract delivered or issued for delivery in this State which provides that coverage of a dependent child of an employee or other member of the coverage group terminates upon attainment of the limiting age for dependent children specified in the policy or contract shall also provide in substance that attainment of the limiting age does not operate to terminate the coverage of the child while the child is and continues to be both (a) incapable of self-sustaining employment by reason of intellectual disability or physical handicap, and (b) chiefly dependent upon the employee or member for support and maintenance, as long as proof of the incapacity and dependency is furnished to the insurer by the employee or member within thirty-one days of the child's attainment of the limiting age and subsequently as may be required by the insurer, but not more frequently than annually after the two-year period following the child's attainment of the limiting age.
S.C. Code § 38-71-780