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When an ACH Transaction Fails Because of a Bad Account Number
ACH payments are popular for their speed and convenience—but they rely on every piece of information being accurate. If the account number provided for a transaction is invalid, the payment won’t go through. Instead, it’ll bounce back with ACH Return Code R43.
This return code means the account number you submitted doesn’t match what the receiving bank (DFI) has on record. It’s a common issue with a clear fix—once you understand what caused it.
Let’s take a look at what R43 – Invalid DFI Account Number means, what leads to this error, and how to resolve it quickly.
What Does ACH Return Code R43 Mean?
ACH Return Code R43 stands for:
“Invalid DFI Account Number.”
Here’s how NACHA officially defines it:
R43 – Invalid DFI Account Number: The account number structure included in the entry is not valid for the receiving bank (DFI – Depository Financial Institution).
In simple terms: the bank account number submitted for the transaction doesn’t follow the correct format—or doesn’t exist—according to the receiving bank.
What Causes an R43 ACH Return?
Here are the most common reasons you might see an R43 return:
Account number contains too many or too few digits
Invalid characters (such as letters or special symbols) were entered
Typos during manual entry
Account number doesn’t match any account at the receiving bank
Outdated account info after a customer changed banks
Mismatched routing and account number combination
This return code doesn’t necessarily mean the account is closed—it simply means the number can’t be processed as entered.
How to Handle ACH Return Code R43
Here’s what to do if a transaction comes back with an R43 code:
1. Check the Account Number in Your Records
Compare what was submitted in the ACH file to what you have on file. Look for missing digits, transposed numbers, or extra characters.
2. Contact the Customer or Recipient
Ask them to confirm their full account number and routing number. If they’ve recently changed banks or updated their account, they may have forgotten to notify you.
3. Verify Account Format
Some banks have specific formatting rules or account number lengths. Make sure the number you were given matches the expected structure for the financial institution.
4. Update and Resubmit
Once you have the correct information, update your records and resubmit the transaction.
How to Avoid R43 Errors in the Future
Here are a few simple steps that can help you avoid R43 returns:
Use account verification tools that confirm whether an account number is valid before submitting a transaction
Double-check data entry, especially when manually inputting routing and account numbers
Encourage customers to provide a voided check for accurate bank details
Train staff on proper data entry procedures and common formatting issues
Update customer info regularly, especially if a transaction fails more than once
Taking a few minutes to confirm account numbers at the start can prevent days of delay later on.
Get ACH Processing With Durango
ACH Return Code R43—“Invalid DFI Account Number”—means the account number used in the transaction doesn’t match the format or structure expected by the receiving bank. It’s a simple issue, but one that can cause frustration if not resolved quickly.
At Durango Merchant Services, we help businesses stay on top of ACH compliance, reduce avoidable return codes, and streamline payment collection. Whether you’re processing high volumes of ACH transactions or just getting started, our team is here to help you send payments that land exactly where they’re supposed to.
