Conn. Gen. Stat. § 52-139: Set-off of mutual debts; procedure.

(a) In any action brought for the recovery of a debt, if there are mutual debts between the plaintiff or plaintiffs, or any of them, and the defendant or defendants, or any of them, one debt may be set off against the other.

(b) No debt claimed by assignment may be set off unless the plaintiff had notice, at the commencement of the action, that the debt was due the defendant.

(c) If it appears upon the trial that the plaintiff is indebted to the defendant, the court shall give judgment for the defendant to recover the balance due of the plaintiff with his costs, except that no judgment may be given against the plaintiff to recover the balance of a debt due only a part of the defendants.