An ABA number is a nine-digit code that identifies a specific bank or credit union in the United States
The ABA number (also called a routing number or routing transit number) tells the banking system which institution holds an account. When you send money to someone else's account—whether by wire transfer, ACH payment, or check—the ABA number is how the sending bank knows where to route that money. Without it, the payment system would not know which of thousands of banks to send your funds to.
The number is managed by the American Bankers Association, which is why it carries that acronym. Each bank and credit union has its own ABA number. A large bank with branches across multiple states may have different ABA numbers for different regions or divisions, so the number is tied to a specific location or processing center, not just the bank's name.
You will see the ABA number printed on the bottom left of your checks. It is also available through your bank's website, your account statements, or by calling customer service. The number never changes for your account—it is a permanent identifier for that institution.
Key Takeaways
- An ABA number is a nine-digit code that identifies which bank or credit union holds an account, used by the payment system to route money correctly.
- The number appears on the bottom left of checks and is available through your bank's website, statements, or customer service.
- Different branches or divisions of the same bank may have different ABA numbers, so the code identifies a specific processing location, not just the bank name.
- You need the ABA number of the receiving bank (not your own) when you send a wire transfer, set up an ACH payment, or provide banking details to an employer or creditor.
- The ABA number is distinct from your account number—together they form the complete routing information a bank needs to find the right account.
Where the ABA number appears and how to find yours
The easiest place to locate your ABA number is the bottom left corner of any check you have written. The first nine digits printed there are your routing number. If you do not have checks or prefer not to look them up that way, log into your bank's website or mobile app—most institutions display the routing number in the account details or settings section.
You can also call your bank's customer service line and ask for your routing number. Have your account number ready, though the representative can usually look it up by your name and account type. Some banks print the routing number on statements as well, though this varies by institution.
If you need the ABA number for a bank other than your own—for instance, to receive a wire transfer or set up a direct deposit—you can ask that bank directly, or search the Federal Reserve's routing number database online. The database is public and searchable by bank name and state.
Why banks need the ABA number for payments to move
The U.S. payment system processes millions of transactions daily. When you initiate a wire transfer or an ACH payment (automatic clearing house, used for direct deposits and bill payments), the sending bank needs to know exactly where to send the money. The ABA number is the address that tells the system which bank to contact.
Think of it like a postal code for banks. Your account number identifies your specific account, but the ABA number identifies the bank that holds it. Without the ABA number, the sending bank would not know whether to route your payment to Bank of America in New York or Bank of America in California, or to a completely different institution with a similar name.
The routing happens through the Federal Reserve or through private clearing networks, depending on the type of payment. Either way, the ABA number is the first piece of information the system uses to sort the transaction to the correct destination.
The difference between an ABA number and an account number
These two numbers work together but serve different purposes. Your account number identifies your specific account at the bank—it is unique to you and your account type (checking, savings, money market). Your ABA number identifies the bank itself. You need both pieces of information for someone to send you money.
When you provide banking details to an employer for direct deposit, you give them both numbers. The ABA number tells their payroll system which bank to contact. The account number tells that bank which account to deposit the money into. If you provide only one, the payment cannot go through.
Your account number is usually longer than nine digits and appears on your checks, statements, and online banking portal. It may also appear on your debit card, though not always. The ABA number is always nine digits and is the same for all customers at that bank's branch or processing center.
When you need to provide an ABA number
You will need to provide the ABA number of your bank in these situations: setting up direct deposit with an employer, arranging automatic bill payments, receiving a wire transfer from someone outside your bank, or setting up transfers between your accounts at different institutions.
You will also need it if you are receiving a payment from a government agency, a tax refund, or a settlement. The payer will ask for your bank's ABA number and your account number so they can deposit the funds correctly.
In most cases, you provide the ABA number of the bank that will receive the money, not your current bank. If you are setting up a transfer from your checking account to a savings account at a different bank, you would give the ABA number of the bank that holds the savings account.
What happens if you use the wrong ABA number
If you provide an incorrect ABA number, the payment may be rejected before it is sent, or it may be sent to the wrong bank. If it reaches the wrong bank, that institution will typically reject it because the account number will not match any account in their system. The money will then be returned to the sender, though this can take several business days.
If the wrong ABA number happens to route the payment to a real bank where an account with that number exists, the money could be deposited into someone else's account. This is rare but possible. For this reason, it is important to double-check the ABA number before you authorize a payment, especially for large amounts or one-time transfers.
Wire transfers are harder to reverse than ACH payments, so verify the routing information carefully before sending a wire. If you are unsure, contact the receiving bank directly and confirm the correct ABA number and account number before you proceed.
ABA numbers for credit unions and online banks
Credit unions also have ABA numbers, assigned and managed the same way as traditional banks. If you have an account at a credit union, you can find the routing number on your checks, through your online banking portal, or by calling the credit union directly.
Online banks and digital-only financial institutions also have ABA numbers. These banks do not have physical branches, but they still participate in the Federal Reserve's payment system and maintain routing numbers for ACH transfers and wire transfers. You will find the routing number on the bank's website or in your account information.
Some online banks display the routing number prominently because many customers need it for direct deposit setup. If you cannot find it on the website, log into your account or contact customer service—they can provide it when ready.
Frequently Asked Questions
Is my ABA number the same as my bank's ABA number?
Yes. The ABA number belongs to the bank, not to your individual account. All customers at the same bank branch or processing center share the same ABA number. Your account number is what makes your account unique within that bank.
Can I use someone else's ABA number to send them money?
You need the ABA number of the bank that holds their account, not their personal ABA number (they do not have one). If you are sending money to someone at Bank of America, you use Bank of America's ABA number along with their account number. The ABA number is public information.
Do I need an ABA number to receive a wire transfer?
The person sending the wire needs your bank's ABA number and your account number. You do not need to do anything with the ABA number yourself—you just provide those two pieces of information to the sender, and they handle the rest.
What if my bank has multiple ABA numbers?
Large banks sometimes have different ABA numbers for different regions or divisions. Make sure you are using the correct one for the specific branch or processing center that holds your account. Your checks or online banking portal will show you the right number to use.
Can the ABA number change?
No. Your bank's ABA number is permanent. It does not change if you move, change account types, or stay with the bank for decades. The only time it would change is if your bank merges with another institution or restructures its processing centers, which is rare and would be communicated to you by the bank.