DECISION ORDER
ORDERED that the order is reversed, on the law, with costs, and the motion is denied.
"[A] document comes within CPLR 3213 `if a prima facie case would be made out by the instrument and a failure to make the payments called for by its terms'" (Weissman v. Sinorm Deli, 88 N.Y.2d 437, 444 , quoting Interman Indus. Prods. v. R.S.M. Electron Power, 37 N.Y.2d 151, 155 ). "The instrument does not qualify if outside proof is needed, other than simple proof of nonpayment or a similar de minimis deviation from the face of the document" (Weissman v. Sinorm Deli, supra, at 444). "Where the instrument requires something in addition to the defendant's explicit promise to pay a sum of money, CPLR 3213 is unavailable" (Weissman v. Sinorm Deli, supra, at 444). In the case at bar, since outside proof was required to determine the sum due upon the promissory note at issue in the event of default, the granting of the plaintiff's motion for summary judgment in lieu of complaint was inappropriate.