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 California, writing a bad check can be a criminal offense under California Penal Code Section 476a. This statute applies when a person writes a check knowing that there are insufficient funds in the account, or the account is closed, to cover the check. The crime can be charged as a misdemeanor or a felony, depending on the amount of the check and the defendant's criminal history. For checks less than $950, it is usually a misdemeanor, while checks of $950 or more can be charged as a felony. Additionally, if a person writes a check from one account and deposits it into another account (check kiting), and then withdraws the funds before the check clears, this can also lead to criminal charges. While occasional mistakes may not lead to prosecution, repeated incidents or evidence of intent to defraud can result in criminal charges. The prosecutor must show that the person had knowledge that the check would not be honored, but does not need to prove the exact balance in the account at the time the check was written.