At what point does the check-writing bank confirm the check is legitimate?

When a check's status changes from pending to clearing, the payee bank receives it. Typically, payee banks return most checks within 24 hours of receiving them. The most common reasons for returns within this time period are insufficient funds, account closed, or a stop payment. Duplicate presentment, which occurs when a check is deposited multiple times, can be returned at any time. Returns for altered checks can be made within 18 months based on the Uniform Commercial Code of the payee's bank state.