You generally have up to 30 days from the statement date to notify the bank of an error, including an unauthorized signature or an unauthorized alteration on a check. Please note: the time periods for prompt notification may vary by bank and state. If you have an account with multiple forgeries (for example, stolen checks), you should consider closing the account.
You are responsible for reviewing your periodic statement and notifying the bank of errors in a timely manner. Review your deposit account agreement for policies specific to your bank and your account