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

Don't you mean International Bank Account Number? If yes, this is a regex for IBAN (all IBANs):

[a-zA-Z]{2}[0-9]{2}[a-zA-Z0-9]{4}[0-9]{7}([a-zA-Z0-9]?){0,16}

UPDATE: Actually, according to Wikipedia: Banks in the United States do not provide IBAN format account numbers. Any adoption of the IBAN standard by U.S. banks would likely be initiated by ANSI ASC X9, the U.S. financial services standards development organization but to date it has not done so. Hence payments to U.S. bank accounts from outside the U.S. are prone to errors of routing.

Answer 2

You can validate the routing number (or ABA) by downloading the DB (fixed field width text format) from the federal reserve bank. The data is here: https://www.frbservices.org/EPaymentsDirectory/fpddir.txt and the layout describing the data is here: https://www.frbservices.org/EPaymentsDirectory/fedwireFormat.html

There are companies (lyonslive.com) that offer a webservice to validate account numbers but they charge per validation (volume based pricing starting @ 60 cents per check - if volume is high enough it can be as low as 24 cents).

Answer 3

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.

Answer 4

There is no standard for a bank account number in the US. There is a standard for the routing number, because that's shared between banks; the account number, however, is only of use internally by the bank itself.

Answer 5

I don't think there is a standard - different institutions seem to use different lengths of account number. There probably is an upper limit - it is unlikely to be less than 20.

Answer 6

There is no standard for US banks' account numbers.

IBAN is not used in the US.

There is a limit for ACH transactions (4-17 digits), but not all transactions have to be ACH.

And yes, the US banking system is antiquated.

I'm looking at a DW (Data Warehouse) of 38 different systems at a bank and the length of account varies widely depending on the product. Several of the systems have alphabetic characters in the account numbers. This is probably irrelevant since they are special types of customer accounts like brokerage accounts and other things which aren't accessible through ACH - you need to specify what kind of account you're interested in. If you restrict yourself to accounts which you can get to through ACH, you can simply restrict to numeric digits.

You can get a lot more information about ACH at: http://www.nacha.org/