Answers about Bank Errors
How long can the bank take to correct an electronic funds transfer (EFT) error and credit the checking account?
Generally, a national bank can take up to 10 business days to determine if an EFT error has occurred. The bank should respond to you within three business days of completing its investigation.
If the bank cannot make a decision within 10 business days, it may take up to 45 days to determine if an error has occurred. In this case it must provisionally (temporarily) reimburse your account. (Note: Depending on the type of transaction, the 45-day limit can be extended.)