What is ABA Number? Where to Find? How Does It Work? (Detailed)

Banks and Financial Institutions in the USA need to use a routing number at the time of sending and receiving money from other Banks, Financial Institutions, and Credit Unions.

The number is called the aba number. ABA means the American Banking Association. It is a nine-digit number. Financial Institutions, Banks, and Credit Unions in the country are provided with such a number. Without this number, these organizations will not be able to send or receive any money from any of the peering organizations.

American Bankers Association (ABA) Origins

In 1910, the American Bankers Association (ABA) created ABA numbers to identify and assign each payment issuing bank in America. This helps in reducing the confusion for making check payments that were common at that time and the only way to process payments.

Over time, the ABA numbers evolved, and now it helps in processing the electronic payments, works as a routing number.

Working Policy of ABA Number

Banks, financial institutions, and all credit unions utilize aba number.  It helps them to activate all the financial dealing materialized. It is alternatively referred to as the routing transit number of a bank. This number helps other banks, Financial Institutions, and Credit Unions determine where an account was opened.

American Bank Association Number helps bank staffs and the machines from getting confused at the sight of Bank, Financial Institutions, and Credit Unions with a similar name. It also helps them understand where a check or money transaction order is destined for.

ABA Number

With its’ help, Checks intended for American Express or Bank of America never are sent to the wrong destination even by mistake.

Bank, Financial Institutions, and Credit Unions may have different ABA numbers. Being such a thing depends on various factors. These may include the location of an account and/or the task for which the number is assigned.

It can assure that no two banks will ever have the same American Bank Association Number.

The aba number appears in two forms on most of the checks. The prime one is the machine-readable nine-digit number on the bottom. It is followed by the checking account number, as a fraction on the top,

The first form, more popularly known as Magnetic Ink Character Number or MICR, is used to process checks in this form.

The latter is the holdover. It records the time when checks are processed manually. It contains most of the same information as referred in the first form in a different format.

The format is still used as a backup if the MICR format does not work. The insertion of the number printed in MICR allows the system to recognize the same.

How to Find ABA Number? 

You can get the ABA number that is linked to the bank account from various available sources. You can even look at the checkbook as it would be handy to get this number. Let’s have a look at all possible sources to find the ABA number.

Paper Checks – 1

You will find the ABA number on the bottom of every check you are holding in your checkbook. For instance, one can look at the right-side bottom of the personal check slip to find this number. For the information, the ABA number is a nine-digit transit number. Sometimes, it does mention differently in the case of online generated checks or slips.

Contact Bank – 2

The second option to find this number is via contacting the bank. Some banks provide such information online, and some banks require customer login to the online banking portal for giving access to the transit numbers.

You can also search at the bank website for direct deposit form or ACH (Automated Clearing House) information. Alternatively, one can contact the customer service of the particular bank for any further information.

Customer Service – 3

Last, one can directly reach the customer service of the bank to know about the correct ABA number. It is because knowing the correct number is essential for ordering checks online, or one also needs a different number for completing wire transfers. (You will have to confirm with the bank for all these transactions and a particular number.)

How Does ABA Number Work?

Americal Banking Association Transit Number is normally used to receive online payments – for instance, a paycheck.

For facilitating your employer to pay the salary directly to your account, you will have to provide the aba number along with the checking account number. Your bank is supposed to assume the rest of the responsibilities.

Checks sent for credit to your account will be electronically verified against all the information provided. Then, it will be credited within a stipulated period.

ABA numbers follow the intricate system of the bank;

Behind the name – 

It is like an address that tells financial institutions the address of the bank account. It generally addresses the location of the bank where the account is getting managed. Thus, it also works as routing transit numbers (RTNs) or check routing numbers.

Computer Readable –

The routing numbers are generally placed on the checks using magnetic ink. This makes it easy to read for the MICR machines. It does not matter either the magnetic ink is used or not, but with the help of a computer, the digits are easily readable.

  • The first four digits of the routing number are assigned by the federal reserve routing system. It is generally to assign bank location in the first four digits of ABA numbers.
  • The fifth and sixth digits are especially for routing wire payments.
  • The seventh digit indicates the check processing center that is assigned to the particular bank.
  • The eighth digit indicates the actual location of the bank.
  • The ninth digit is for completing the checksum.


Without an aba number, no Bank, Financial Institution, or Credit Union can continue their business. However, there are qualifying terms in this regard.

Such an institution must have eligibility to hold an account at any of the Federal Reserve Bank.

American Banking Association Number is currently managed by Accuity. It is a professional banker registration unit, listed in the USA.

Author: Naveen EThis is E.Naveen Kumar full time Content Writer, SEO, Digital marketing Expert, founder of financesrule.com. Really enjoying playing cricket at free times. Being a Btech Graduation from Computer Science stream Selected full-time blogging as my Profession.

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