In Illinois, in its simplest terms, forgery can be understood as the knowing and willful falsification of signatures, documents, or objects. Common forged documents include checks, contracts, wills, and identification cards.A person commits forgery when, with intent to defraud, he or she knowingly: (1) makes a false document or alters any document to make it false. Illinois forgery charges are very serious, as forgery is generally classified as a felony. The penalties are severe, depending on the type of document forged. The writing must be false. Illinois Forgery Laws at a Glance​​ The following table highlights the main provisions of Illinois's forgery laws, including penalties and sentencing.