What Is the Punishment for Forging a Signature on a Check? What Is the Difference Between Forgery and Counterfeit?Forgery, deceive or injure another, he falsely makes, completes or alters a written instrument which is or purports to be. Of course jail time is possible — or even likely — for forging documents in NYS, just as it is everywhere the rule of law applies. The forgery provisions of the Penal Law are found in Article 170. There are three degrees each of forgery and criminal possession of a forged instrument.