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 Connecticut, writing a bad check, also known as issuing a check with non-sufficient funds (NSF), is addressed under the state's penal code. The act becomes a criminal offense when a person knowingly writes a check without having sufficient funds in their account, or writes a check on an account that is closed. Additionally, it is considered a crime if someone writes a check for more than the available balance and then withdraws funds from a second account before the check is processed by the first bank. While occasional mistakes can happen, Connecticut law focuses on the intent or knowledge of the individual at the time the check was written. The state does not require prosecutors to prove the exact balance in the account at the time of writing the check, but rather that the individual had the requisite knowledge or intent to commit the offense of writing a bad check. Penalties for writing bad checks in Connecticut can range from fines to imprisonment, depending on the amount of the check and other circumstances surrounding the offense.