S.C. Code Ann. § 12-8-1520 — Withholding agents' duties to deposit and pay withholdings

(A)(1) Resident withholding agents who deposit and pay withholding to the Internal Revenue Service under the provisions of the Internal Revenue Code as defined in Section 12-6-40(A) and applicable regulations shall remit all South Carolina taxes withheld pursuant to this chapter on or before the date their federal withholding taxes are due.
(2) If a resident withholding agent is required under the Internal Revenue Code to deposit withheld funds at a financial institution, then the withholding agent shall deposit the funds required to be withheld under this chapter at a financial institution selected by the State Treasurer, unless otherwise instructed by the department.
(3) If a resident withholding agent is not required to deposit and pay federal withholding to the Internal Revenue Service under the provisions of the Internal Revenue Code and applicable regulations, the resident withholding agent shall remit South Carolina withholding to the department in accordance with subsection (B).
(B) A nonresident withholding agent and a resident withholding agent described in (A)(3) must remit South Carolina taxes withheld under this chapter as follows:
(1) on or before the fifteenth day of the month following the month in which the aggregate amount withheld is five hundred dollars or more; or
(2) on or before the last day of the month following the quarter in which funds were withheld if the aggregate amount withheld in a calendar quarter is less than five hundred dollars.
(C) In order to maintain conformity with the federal withholding system, the department may by rule adopt new federal withholding regulations.
(D) Any withholding agent making at least twenty-four payments in a year must do so as provided in Section 12-54-250.