From Florida Legal Wiki
Payment is an Affirmative Defense. The elements are somewhat self evident, requiring that the Defendant show he paid the amount which is claimed by the Plaintiff to be due and owing. Payment is an affirmative defense that must be plead. Goldberger v. Regency Highland Condo. Ass'n, Inc., 452 So.2d 583, 585 (Fla. 4th DCA 1984), citing Connecticut Bank & Trust Co. v. Dadi, 438 A.2d 733, 735 (1980) ("Payment, even though nonpayment has been alleged by the plaintiff, must be specially pleaded as a defense").