United States Banking Institution Account Number Regular Expression?

Question

I have been tasked to \"verify\" the length of a U.S. Banking Institution ACCOUNT NUMBER for a web app I\'m developing. I cannot find anything through SOF, Google, Fed reser

Answer 1

Good luck with that, because you can't.

Banks are free to use just about anything as an account number. I think the only validation you can do is whether or not they're numeric (as they all are).

The most common length for bank account numbers is 9, 12, or 10 digits. Although they range from 4 to 17 digits long. I have a large database of valid numbers and there's no pattern that I can see to the "account number".

A "routing number" defines the bank (pretty much) but even within a particular routing number, the account numbers can be of different lengths.

This is why payroll services often require an extra day (or two) before initiating Direct Deposit in order to "prenote" the account (validate it by performing a no-op ACH transaction) because you really can't verify it otherwise.