S.C. Code Ann. § 12-2-75: Signatories to tax returns.

(A) Returns filed by taxpayers with the department must be signed by the following:

(1) corporate returns by an authorized officer of the corporation;

(2) partnership returns by its manager or an authorized general partner of the partnership;

(3) trust and estate returns by the trustee, personal representative, executor, or administrator, whichever is applicable;

(4)(a) except as provided in subitems (b) and (c), individual returns must be signed by the individual;

(b) deceased individual returns for individuals who would have been required to file a state tax return while living by the personal representative, administrator, or executor of the decedent's estate and the tax must be levied upon and collected from the estate;

(c) if an individual is unable to make a return or payment, including an estimated tax payment, it must be made by an authorized agent, a guardian, or other person charged with the conduct of the business of the taxpayer;

(5) returns for any other person by an authorized officer or owner.

(B) In the instructions to a return, or otherwise, the department may authorize taxpayers to sign returns by other means, including electronically, and may authorize the signature to be filed or deposited with and be kept or forwarded by a third party. To the extent that a tax return preparer, as that term is defined in Internal Revenue Code Section 7701(a)(36), is required or permitted to sign a return, the department in the instructions to a return, or otherwise, may authorize the tax return preparer to sign the return by other means, including electronically.