An ABA number is a nine-digit code that identifies which bank holds your account
The ABA number (also called a routing number) tells the banking system which specific bank or credit union you use. When money moves between accounts—whether you're setting up direct deposit, sending a wire transfer, or paying a bill through your bank—the ABA number is how the system knows where to send it. Without it, your payment could end up at the wrong bank or get stuck in processing.
The American Bankers Association created this numbering system decades ago, which is why it's called an ABA number. Every bank and credit union in the United States has at least one ABA number, and some large institutions have multiple numbers for different branches or services. Your bank's ABA number stays the same; it doesn't change when you open a new account or move branches.
Key Takeaways
- An ABA number is a nine-digit code specific to your bank or credit union, not to your individual account.
- You need your ABA number whenever you set up direct deposit, request a wire transfer, or authorize automatic bill payments.
- Your bank's 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 public information—sharing it does not put your account at risk because it only identifies the bank, not your specific account.
Where to find your ABA number
The easiest place to find your ABA number is on a check from your account. Look at the bottom left corner of the check—the first nine digits printed there are your ABA number. The next set of numbers is your account number, and the last set is the check number.
If you don't have checks handy, log into your online banking portal or mobile app. Most banks display the routing number (ABA number) in the account details section, sometimes labeled as "routing number" or "bank routing number." You can also call your bank's customer service number on the back of your debit card and ask for the routing number—they'll give it to you immediately.
Some banks also post their routing number on their website. Search "[your bank name] routing number" and you'll usually find it listed on their customer service or FAQ page.
Why banks ask for it during transfers and deposits
When you set up direct deposit for a paycheck or government payment, your employer or the paying agency needs to know which bank to send the money to. The ABA number is part of that instruction. Without it, the system doesn't know whether you bank at Chase, Bank of America, a local credit union, or somewhere else entirely.
Wire transfers work the same way. If you're sending money to someone at a different bank, you provide their ABA number so the wire goes to the correct institution. Automatic bill payments also use the ABA number to route money from your account to the company you're paying.
Some services ask for both your ABA number and your account number together. The ABA number identifies the bank; your account number identifies you within that bank. Together, they create a complete routing path for your money.
The difference between ABA numbers and account numbers
Your account number is unique to you—it identifies your specific checking or savings account at the bank. Your ABA number identifies the bank itself and is shared by everyone who banks there. Think of it this way: the ABA number is the bank's address, and your account number is your mailbox within that building.
If you have multiple accounts at the same bank (a checking account and a savings account, for example), they share the same ABA number but have different account numbers. If you move to a different bank, your ABA number changes but your account number at the new bank will be different too.
For security, your account number is sensitive information you should protect. Your ABA number is public—it's printed on every check you write and appears on bank statements. Sharing your ABA number alone cannot put your account at risk because it doesn't identify which account is yours.
What happens if you use the wrong ABA number
If you provide an incorrect ABA number, the money usually goes to the wrong bank. The receiving bank will eventually notice the error and send it back, but this can take several business days. During that time, your money is in limbo and you won't have access to it.
For direct deposits like paychecks or tax refunds, using the wrong ABA number means your payment arrives at a different bank. The employer or government agency may retry the deposit, or they may mark it as failed and you'll have to contact them to resubmit with the correct information. This can delay your payment by a week or more.
Always double-check the ABA number before you submit it. If you're unsure, call your bank and confirm the number over the phone rather than guessing.
ABA numbers for different types of accounts
Most checking and savings accounts at the same bank share one ABA number. However, some banks use different routing numbers for different services. For example, a bank might have one ABA number for standard transfers and a different one for wire transfers, or one for checking accounts and another for savings accounts.
Credit unions also have ABA numbers, and they work the same way as bank routing numbers. If you're a credit union member, you can find your routing number on your checks or by calling the credit union directly.
Online banks and smaller regional banks have their own ABA numbers too. The system is universal across all financial institutions in the United States, so the process for finding and using your routing number is the same whether you bank with a large national chain or a small local credit union.
Frequently Asked Questions
Can someone steal money from my account if they have my ABA number?
No. Your ABA number only identifies which bank you use, not which account is yours. A person would need both your ABA number and your account number to access your account, and even then, most transfers require additional verification like a password or security code. Never share your full account number with people you don't trust, but the ABA number alone is safe to share.
Do I need a different ABA number for each account I have?
No. All your accounts at the same bank—checking, savings, money market—use the same ABA number. The account number is what distinguishes one account from another. If you move to a different bank, your new accounts there will have a different ABA number but the same principle applies.
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 routing number. Your bank will notify you of any change and update your account information. If you have direct deposits or automatic payments set up, contact your employer or service providers to update the routing number if your bank tells you it has changed.
Is the ABA number the same as the SWIFT code?
No. The ABA number (routing number) is used for domestic transfers within the United States. A SWIFT code is used for international wire transfers and identifies banks worldwide. If you're sending money to someone outside the U.S., you'll need their bank's SWIFT code, not the ABA number.