Routing Transit Number - ABA Number Management

ABA Number Management

Since 1911, the American Bankers Association has assigned transit numbers through a series of registrars, currently Accuity. The company is responsible for assigning new ABA numbers. Accuity publishes the ABA Number Directory in the American Bankers Association Key to Routing Numbers semi-annually.

There are approximately 26,895 active routing and transit numbers currently in use. Every financial institution in the United States has at least one of these. Multiple RTNs may result from mergers.

ABA numbers are only for use in domestic transactions within the United States and are of two types, one for funds being debited or credited to or from accounts and one that is used for wire transfers. They are different and usually the ABA number on a check book which is usually the middle set of nine numbers printed at the bottom of the check is the former. Domestic transfers that use the debit/credit routing number will usually be returned to the sending bank. Incoming international wire transfers use a different code system call SWIFT-BIC, BIC code, SWIFT ID or SWIFT code more of which can be read about under ISO 9362. There are a number of overlapping issues between these codes and complicating the matter is the fact that European Banks use an IBAN code.

The IBAN was originally developed to facilitate payments within the European Union but the format is flexible enough to be applied globally. It consists of an ISO 3166-1 alpha-2 country code, followed by two check digits that are calculated using a mod-97 technique, and Basic Bank Account Number (BBAN) with up to thirty alphanumeric characters. The BBAN includes the domestic bank account number and potentially routing information. The national banking communities decide individually on a fixed length for all BBAN in their country.