
230 S.E.2d 201 (1976)
31 N.C. App. 561
Harold E. DRIGGERS
v.
COMMERCIAL CREDIT CORPORATION et al.
No. 7618SC434.
Court of Appeals of North Carolina.
December 1, 1976.
*202 Max D. Ballinger, Greensboro, for plaintiff.
Smith, Moore, Smith, Schell & Hunter, by J. Donald Cowan, Jr., Greensboro, for defendant Commercial Credit Corp.
BROCK, Chief Judge.
The only question properly before us for review is the interpretation placed upon G.S. 1A-1, Rule 13(a), by the trial judge. We express no opinion upon Driggers' allegations of fraud or the alleged damages arising therefrom.
The pertinent provisions of G.S. 1A-1, Rule 13(a), are:
"A pleading shall state as a counterclaim any claim which at the time of serving the pleading the pleader has against any opposing party, if it arises out of the transaction or occurrence that is the subject matter of the opposing party's claim . . ."
As can be seen, the rule refers to a claim which the pleader has at the time of serving the pleading.
Driggers' answer in the prior action was served on 19 November 1973. On 1 February 1974 Driggers sought a copy of the contract sued upon by Commercial Credit. Finally in January 1975 an order was entered requiring Commercial Credit to produce the contract. Instead of producing the contract signed by Driggers, Commercial Credit produced a "duplicate" which contained a carbon impression of Driggers' signature. It was under the terms of this "duplicate" contract that Commercial Credit was proceeding in its action against Driggers. It was not until the day of trial in February 1975 that Driggers learned of the difference between the terms of the contract that he had signed and the terms of *203 the "duplicate" contract which had been inserted to obtain the carbon impression of his signature. As soon as this difference in terms was brought to light, Commercial Credit submitted to a voluntary dismissal of its action with prejudice.
In North Carolina an action for fraud accrues when the aggrieved party discovers the facts constituting the fraud, G.S. 1-52(9), or when, in the exercise of reasonable diligence, such facts should have been discovered. Wilson v. Development Co., 276 N.C. 198, 171 S.E.2d 873 (1970). There is nothing in the record before us to suggest that Driggers knew or should have known, at the time he filed his pleading in the former action, of the existence of the "duplicate" contract containing terms different from the one that he signed. Indeed, it was not until the day of the trial in February 1975 that Commercial Credit allowed the discrepancy to come to light. This was more than a year after Driggers had served his answer on Commercial Credit. Driggers undertook to learn of the terms of the contract as early as February 1974, but by reason of Commercial Credit's failure to strictly comply with the court order, Driggers was only furnished the "duplicate" contract. Nevertheless, Commercial Credit seems to argue that Driggers should have opposed its effort to take a voluntary dismissal in the former action. In this way Commercial Credit argues that Driggers should have sought leave to amend his answer to assert the counterclaim in the prior action.
Where a cause of action, arising out of the transaction or occurrence that is the subject matter of the opposing party's claim, matures or is acquired by a pleader after he has served his pleading, the pleader is not required thereafter to supplement his pleading with a counterclaim. Although G.S. 1A-1, Rule 13(e), permits the court to allow such supplemental pleading to assert a counterclaim, such supplemental pleading is not mandated and failure to do so will not bar the claim. See 3 Moore's Federal Practice, ¶ 13.32.
Since there is no showing that Driggers knew or by the exercise of reasonable diligence should have known of his alleged claim for fraud at the time he served answer in the prior action, his claim falls within the exception to Rule 13(a) and constitutes a permissive, not compulsory, counterclaim. His failure to assert his claim in the prior action is therefore not a bar to his present action.
Reversed and remanded.
VAUGHN and MARTIN, JJ., concur.
