S.C. Code Ann. § 8-11-93

Because of the high cost to be borne by the State in providing administrative services regarding payroll deductions for contributions to charitable organizations, even though an organization may be eligible under Section 8-11-92 no such deductions shall be authorized by the Comptroller General, or by the chief finance officer of a state agency or institution maintaining separate payroll accounts, unless at least ten percent of the employees or two hundred employees, whichever shall be the lesser, who are paid from such payroll account, have made a written authorization to deduct contributions to an eligible charitable organization or group of such organizations.