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, direct deposit, or automatic payment. Every bank and credit union in the United States has its own ABA number. When someone sends you money electronically, they use your ABA number plus your account number to make sure the funds land in the right place.
The ABA stands for American Bankers Association, the organization that originally assigned these codes decades ago. The system is still used today by the Federal Reserve, the Automated Clearing House (ACH), wire transfer networks, and check processing systems. If you have accounts at multiple banks, each one has a different ABA number — even if you bank with the same institution in different states, the branch location can matter.
Key Takeaways
- An ABA number is a nine-digit code unique to each bank or credit union branch, used to route electronic transfers and direct deposits to the correct institution.
- You need your ABA number whenever you set up direct deposit, authorize automatic bill payments, or receive a wire transfer from another person or organization.
- Your ABA number appears on the bottom left of your checks, in your online banking portal, or by calling your bank's customer service line.
- The ABA number is different from your account number; together they ensure money reaches your specific account at your specific bank.
Where to find your ABA number
The easiest place to locate your ABA number is the bottom left corner of any check you have from that account. The nine digits appear before your account number. If you do not have checks or prefer not to look at them, log into your online banking account — most banks display the routing number in the account details or settings section, sometimes labeled "routing number" or "transit number."
You can also call your bank's customer service number (usually on the back of your debit card) and ask for your routing number. Have your account number ready so they can confirm which account you mean. Some banks also list the ABA number on their website if you search for "routing number" plus your bank name and state.
Why you need it for direct deposit and transfers
When your employer sets up direct deposit of your paycheck, they ask for your ABA number and account number. The ABA number tells the payroll system which bank to send the money to; the account number tells that bank which account within the institution receives it. Without the correct ABA number, the deposit may go to the wrong bank entirely or be rejected.
The same applies when you authorize automatic bill payments from your account — your utility company, insurance provider, or loan servicer needs both numbers to pull money from the right place. If you set up a transfer between your own accounts at different banks, you will need the ABA number of the receiving bank. Wire transfers also require the ABA number of the receiving institution.
ABA numbers for different types of institutions
Banks, credit unions, online banks, and savings institutions all have ABA numbers. A large national bank like Chase or Bank of America has multiple ABA numbers — one for each state or region where it operates. A small community bank or credit union has its own unique ABA number. Online banks that have no physical branches still have an ABA number assigned to them by the Federal Reserve.
If you move your account from one bank to another, your new bank will have a different ABA number. If you open a second account at the same bank, it may have the same ABA number (if it is at the same branch) or a different one (if the branch is in a different state or the bank has reorganized its routing structure). Always confirm the correct ABA number for the specific account and institution you are using.
How ABA numbers differ from account numbers
An account number identifies your individual account within a bank; an ABA number identifies the bank itself. Think of it this way: the ABA number is the address of the bank building, and the account number is your mailbox inside that building. You need both pieces of information for money to reach you.
A typical bank account setup looks like this: ABA number (nine digits) + account number (usually 10 to 12 digits, but varies by bank). On a check, the ABA number appears first on the bottom left, followed by the account number, then the check number on the right. When you provide banking information to an employer or creditor, you will give them both numbers.
What happens if you give the wrong ABA number
If you provide an incorrect ABA number, the transfer or deposit may be rejected by the receiving bank's system before it even processes. Some automated systems catch the error immediately and return the money to the sender. Other times, the money may be sent to a different bank, and you will have to contact that bank and your own bank to trace and recover it — a process that can take several days or longer.
For direct deposits like paychecks, a wrong ABA number usually means the deposit fails and your employer is notified. You would then need to correct the information with payroll and wait for the next pay cycle. For bill payments, a wrong ABA number might cause the payment to fail, which could result in a late fee if the biller does not receive the money on time. Always double-check the ABA number before submitting it for the first time.
ABA numbers and check processing
Banks use ABA numbers to sort and process paper checks. When you write a check, the ABA number on the bottom tells the receiving bank's processing system which institution to collect the funds from. The Federal Reserve and other check-clearing networks use ABA numbers to route millions of checks daily to the correct banks. Even though electronic transfers have become more common, checks are still processed using the same ABA routing system.
If you deposit a check from another person or business, the ABA number on that check tells your bank where to send it for collection. The check-clearing process can take one to three business days partly because the ABA number has to be read and verified at multiple points in the system.
Frequently Asked Questions
Is my ABA number the same as my routing number?
Yes, ABA number and routing number are the same thing. Banks and credit unions use both terms interchangeably. You may see it called a routing transit number (RTN) or routing number, but they all refer to the same nine-digit code.
Can I use someone else's ABA number to send them money?
Yes. If you are sending money to someone else's account, you need their ABA number (the bank's routing number) and their account number. You do not need to know their name or any other personal details — the ABA and account numbers are enough for the system to route the money correctly.
Do I need a different ABA number for each account I have?
Not necessarily. If you have two accounts at the same bank branch, they may share the same ABA number. If you have accounts at different banks or different branches of the same bank in different states, each account will have its own ABA number. Check with your bank if you are unsure.
What if my bank merged with another bank — does my ABA number change?
Sometimes. After a merger, the acquiring bank may assign a new ABA number to accounts from the acquired bank, or it may keep the old one. Your bank will notify you if your ABA number changes, and you will need to update it with your employer, billers, and anyone else who has it on file.
Can I look up someone else's ABA number?
Yes. If you know which bank someone uses, you can search for that bank's ABA number online or call the bank directly. The ABA number is not private information — it is the same for everyone who banks at that institution in that location.