S.C. Code Ann. § 62-2-701
A contract to make a will or devise, or to revoke a will or devise, or not to revoke a will or devise, or to die intestate, if executed after the effective date of this act, can be established only by (1) provisions of a will of the decedent stating material provisions of the contract; (2) an express reference in a will of the decedent to a contract and extrinsic evidence proving the terms of the contract; or (3) a writing signed by the decedent evidencing the contract and extrinsic evidence proving the terms of the contract. The execution of a joint will or mutual wills does not create a presumption of a contract not to revoke the will or wills.
HISTORY: 1986 Act No. 539, SECTION 1; 1990 Act No. 521, SECTION 28; 2013 Act No. 100, SECTION 1, eff January 1, 2014. Part 8 General Provisions