An ABA number is a nine-digit code that identifies the specific bank or credit union where you hold an account

The ABA number — also called a routing number or routing transit number — tells the financial system which institution to send money to when you receive a transfer. When someone pays you by wire transfer, ACH transfer, or check, that nine-digit code is what directs the money to your bank, not someone else's. Without it, the payment system would not know where your account actually lives.

ABA stands for American Bankers Association, the organization that originally assigned these codes in the 1910s. The system has stayed largely the same for over a century because it works: one number, one institution, no ambiguity. Your bank's ABA number is the same whether you have a checking account, savings account, or both.

The number appears on the bottom left of your checks, in your bank's online banking portal, and on statements. If you cannot find it, calling your bank's customer service line will get you the answer in under a minute.

Key Takeaways

  • An ABA number is a nine-digit code that identifies your specific bank or credit union to the payment system.
  • The number appears on the bottom left of checks and in your online banking portal under account or routing information.
  • Different branches of the same bank usually share one ABA number, so you do not need a separate code for each location.
  • Wire transfers, ACH transfers, and direct deposits all require the ABA number to reach the correct account.
  • The ABA number is public information — sharing it does not put your account at risk because a transfer also requires your account number.

How the ABA number fits into a transfer

When you receive money, the sender (or their bank) uses two pieces of information: your ABA number and your account number. The ABA number routes the payment to your bank. Your account number tells that bank which account within the institution receives the money. Together, they form a complete address for your money.

Think of it like mailing a letter: the ABA number is the city and state; the account number is the street address and apartment. The postal service needs both to deliver it to the right place. Without the ABA number, the payment system cannot even begin the delivery.

This matters for timing too. When you initiate a wire transfer, you enter the recipient's ABA number. The sending bank uses it to connect directly to the receiving bank through the Federal Reserve's wire network. That connection is why wire transfers can clear in hours rather than days — the ABA number gets the money to the right place when ready.

Where to find your bank's ABA number

Your ABA number is printed on the bottom left of every check you receive from your bank. It is the first set of nine digits, followed by your account number and the check number. If you have not ordered checks in years, this may not be an option.

Log into your bank's website or mobile app and look for account details, account information, or routing information. Most banks display the ABA number prominently in this section. Some banks also print it on statements, though not all do.

If you cannot locate it online, call your bank's customer service number on the back of your debit card or on your statement. Have your account number ready, and they will provide the ABA number when ready. You do not need to visit a branch.

ABA numbers and branch locations

Most banks use a single ABA number for all their branches nationwide. If you have an account at Chase in New York and transfer money to someone with a Chase account in California, you both use the same ABA number. The account number is what distinguishes your account from theirs.

Some large banks or credit unions with complex structures may have multiple ABA numbers — one per region or one per subsidiary. This is less common but does happen. If you move to a different state or switch branches, your ABA number typically stays the same unless your bank explicitly tells you otherwise.

Credit unions often have different ABA numbers than banks, even if they are in the same town. The ABA number identifies the institution, not the location. If you are unsure whether your credit union has changed its ABA number, ask directly rather than guessing.

Why ABA numbers matter for different types of transfers

Wire transfers require your ABA number because they move money through the Federal Reserve's wire system in real time. The sending bank uses the ABA number to connect to your bank and confirm the account exists before releasing the funds. Without it, the wire cannot be routed.

ACH transfers — the system used for direct deposits, bill payments, and most online transfers between banks — also require the ABA number. ACH is slower than wire (typically one to three business days) but works the same way: the ABA number tells the ACH network which bank to send the money to.

Check deposits work differently. When you deposit a check, the bank reads the ABA number printed on the check itself. That number tells your bank which institution to collect the funds from. If the ABA number on the check is wrong or missing, the check may bounce or be delayed.

ABA numbers and account security

Your ABA number is public information. Banks print it on checks that go through the mail, display it in online portals, and provide it to anyone who asks. Sharing your ABA number alone does not put your account at risk.

A thief cannot transfer money out of your account with only the ABA number. They would also need your account number, and even then, most banks require additional verification before releasing funds. Wire transfers and ACH transfers both have fraud detection systems that flag unusual activity.

That said, do not volunteer your ABA number to unknown sources. If someone calls claiming to be from your bank and asks for it, hang up and call your bank directly using the number on your card or statement. Legitimate banks already know their own ABA number and would not ask you for it.

When you need to provide your ABA number

You will need to provide your ABA number when setting up direct deposit for payroll or government benefits. Your employer or the benefits program uses it to route your payment to the correct bank and account.

If you are receiving a wire transfer from someone outside your bank, you will need to give them your ABA number and account number. They enter both into their bank's wire transfer form, and the money moves to you.

You may also need it when setting up automatic bill payments through your bank, though many banks can look up the ABA number if you provide the company name. Some third-party payment services ask for it as well. In all cases, you are providing it to initiate a payment into your account, not out of it.

Frequently Asked Questions

Is an ABA number the same as a routing number?

Yes. ABA number, routing number, and routing transit number all refer to the same nine-digit code. Banks use the terms interchangeably. You will see all three on bank websites and in documentation.

Can I use someone else's ABA number by mistake?

If you provide the wrong ABA number on a wire transfer or ACH transfer, the money will go to a different bank. That bank will likely reject the transfer because the account number will not match any account in their system, and the money will return to the sender. It is a delay, not a permanent loss.

Do I need a different ABA number for checking and savings accounts?

No. Both accounts at the same bank use the same ABA number. The account number is what distinguishes your checking account from your savings account. When you provide both pieces of information, the bank knows exactly which account to use.

What if my bank merged with another bank?

After a merger, your bank may keep its original ABA number or switch to the acquiring bank's number. Your bank will notify you of any change and update your account information. Old checks with the previous ABA number may still work for a period, but you should order new checks with the current number.

Can I look up someone else's ABA number?

Yes. The ABA number is public information. If you know someone's bank name and location, you can search for the ABA number online using a routing number lookup tool. However, you still need their account number to send them money, and that is private information only they can provide.