S.C. Code Ann. § 12-54-70 — Extension of time for filing returns or paying tax; tentative return and payment of tentative liability

(a) The department may allow further time for the filing of returns or remitting of tax due required by the provisions of law administered by the department. The request for an extension must be filed with the department on or before the day the return of the tax is due. Except as otherwise provided in this section, the department may allow an extension of time not to exceed six months. A tentative return is required reflecting one hundred percent of the anticipated tax to be paid for the taxable period, to be accompanied by a remittance for the tentative tax liability. Interest at the rate provided in Section 12-54-25, calculated from the date the tax was originally due, must be added to the balance due whenever an extension to file or to remit tax due is granted.
(b) If the amount remitted with the tentative return fails to reflect at least ninety percent of the tax to be paid for the period granted by the extension, a penalty as provided in Section 12-54-43(D) must be imposed from the date the tax was originally due on the difference between the amount remitted and the tax to be paid for the period.
(c) Provisions regarding prepayment of ninety percent of the estimated liability do not apply to persons filing monthly reports. For monthly filers, no extension may be granted for more than one additional month beyond the due date. The time and payment requirements of this section do not apply for estate tax purposes if a hardship extension is granted under Section 12-16-1140; but interest must be calculated on any outstanding amount until completely paid.
(d) An extension may not be granted to a taxpayer who has been granted an extension for a previous period and has not fulfilled the requirements of the previous period.