S.C. Code Ann. § 12-37-2170: Penalty for failure to file return or to pay tax.

If any person fails to file a return or to pay a tax, if one is due, on or before the time required by or under the provisions of this chapter, the tax shall be increased by ten per cent, and, in addition thereto, interest at the rate of one-half of one percent per month shall be added to the tax.