S.C. Code Ann. § 12-37-975: Filing of amended return.

The Department of Revenue may permit any person to substitute an amended return for the original return up to the last day prescribed for filing the return, including any extension of time granted by the department. The department in its discretion may accept or reject an amended return filed after the time prescribed for filing the return. An amended return may not operate to start or extend the limitation period for assessment and collection of taxes.