
154 Ga. App. 504 (1980)
268 S.E.2d 777
LLOP
v.
NATIONAL BANK OF GEORGIA.
59329.
Court of Appeals of Georgia.
Submitted February 4, 1980.
Decided May 2, 1980.
Morton P. Levine, for appellant.
Donald J. Goodman, for appellee.
SMITH, Judge.
The National Bank of Georgia (NBG) brought suit on a promissory note against appellant Llop. At the close of the evidence, the trial court granted a directed verdict in favor of NBG. Appellant cites as error the court's exclusion of testimony proffered to establish a parol agreement between the parties subsequent to the subject transaction. We affirm.
"Parol evidence shall be admissible ... to prove a new and distinct subsequent agreement [or] to enlarge the time ... of performance." Code § 38-507. "It, of course, goes without saying that an alleged subsequent agreement, like any other contract, is not binding if it is not supported by a legal consideration, but litigants sometimes get tripped up on this." Green, Ga. Law of Evidence, 491, § 216. Tatum v. Morgan, 108 Ga. 336 (2) (33 SE 940) (1899); J. E. M. Enterprises, Inc. v. Taco Pronto, Inc., 145 Ga. App. 573, 574 (244 SE2d 253) (1978).
Appellant made an offer of proof, attempting to show a subsequent parol agreement with NBG to the effect that he was no longer obligated to pay interest on the subject note and further that he did not have to pay the principal until the conclusion of certain federal litigation to which he was a party. As consideration therefore appellant recited his satisfaction of a separate, past-due obligation and certain token payments made on the subject note. This, however, was not enough, for "[a]n agreement on the part of one to do what he is already legally bound to do is not a sufficient *505 consideration for the promise of another." Johnson v. Hinson, 188 Ga. 639 (2) (4 SE2d 561) (1939). Since NBG's promise to forego further interest and forbear collection was purely gratuitous, the trial court did not err in excluding evidence relating thereto. See Camp & Camp v. Interstate Chemical Co., 18 Ga. App. 416 (4) (89 SE 491) (1916).
Judgment affirmed. McMurray, P. J., and Banke, J., concur.
