Routing number

An ABA routing transit number (ABA RTN) is a nine digit code, used in the United States, which appears on the bottom of negotiable instruments such as cheques to identify the financial institution on which it was drawn. The ABA RTN was originally designed to facilitate the sorting, bundling, and shipment of paper cheques back to the drawer's (check writer's) account. As new payment methods were developed (ACH and Wire), the system was expanded to accommodate these payment methods.

The ABA RTN is necessary for the Federal Reserve Banks to process Fedwire funds transfers, and by the Automated Clearing House to process , bill payments, and other such automated transfers.

The ABA RTN system was developed in 1910 by the American Bankers Association.

Since 1911, the American Bankers Association has partnered with a series of registrars, currently Accuity, to manage the ABA routing number system. Accuity is the Official Routing Number Registrar and is responsible for assigning ABA RTNs and managing the ABA RTN system. Accuity publishes the American Bankers Association Key to Routing Numbers semi-annually. The "Key Book" contains the listing of all ABA RTNs that have been assigned.

There are approximately 26,895 active ABA RTNs currently in use. Every financial institution in the United States has at least one. The Routing Number Policy allows for up to five ABA RTNs to be assigned to a financial institution. Many institutions have more than five ABA RTNs as a result of mergers.

ABA RTNs are only for use in payment transactions within the United States. They are used on paper check, wire transfers, and ACH transactions. On a paper check, the ABA RTN is usually the middle set of nine numbers printed at the bottom of the check. Domestic transfers that use the ABA RTN will usually be returned to the paying bank.

Incoming international wire transfers also use the SWIFT code - a system administered by the Society for Worldwide Interbank Financial Telecommunication (SWIFT). The code is often referred to as "SWIFT-BIC, BIC code, SWIFT ID or SWIFT code". Please see ISO 9362. In addition, European financial institutions use an IBAN code.

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