A person with a bank account writes a bad check (also known as a non-sufficient funds or NSF check) when he deliberately or with knowledge writes a check for an amount of funds he knows are not available in the account. The crime of writing a bad check may also occur when a person writes a check on an account that has been closed. Another bad check scheme that may result in criminal charges occurs when an account holder writes a check for an amount in excess of the funds in the account, and deposits the check in a second account (often at a different bank)—and then withdraws the funds from the second account before the check is presented to the first bank for payment.

Bad check laws vary from state to state, and are usually located in the state’s penal or criminal code (statutes). Banks and criminal prosecutors recognize that a person can inadvertently write a check for more than the funds on deposit in their account, and not every instance will result in criminal charges. But many state laws have an expansive definition of the required knowledge or deliberate intent to write a bad check, and a criminal prosecutor does not have to prove a defendant charged with a bad check offense knew exactly how much money was in the account when the defendant wrote the check to prove the defendant knew he was writing a bad check or deliberately wrote a bad check.

In Illinois, writing a bad check, also known as a non-sufficient funds (NSF) check, can lead to criminal charges under the state's deceptive practices statute (720 ILCS 5/17-1). The law considers it a deceptive practice when a person, with intent to defraud, issues or delivers a check knowing that they do not have sufficient funds in the bank to cover the check. This also applies to checks written on closed accounts. The severity of the offense can range from a Class A misdemeanor for checks less than $150 to a Class 4 felony for checks of $150 or more. For checks of $500 or more without provision for payment in full within 7 days, the offense is a Class 3 felony. Multiple offenses can lead to higher charges. It is important to note that while occasional mistakes may not lead to charges, patterns of behavior indicating intent to defraud can result in criminal prosecution. An attorney can provide guidance on specific cases and potential defenses, such as lack of intent to defraud.