A Guide to ACH Return Codes

For merchants and customers who want to avoid dealing with the credit card payments system, Automated Clearing House payments can seem like an obvious alternative.

However, they are not without their own risks, and it is not uncommon for ACH payments to fail for one reason or another. When this occurs, the receiving financial institution will send back a code that explains why the payment was rejected. Let's take a closer look at ACH return codes and what they mean for merchants.

1. What Are ACH Return Codes?
2. List of Common ACH Return Codes
3. What are the Consequences of an ACH Return?
4. How to Prevent ACH Returns
5. Conclusion

Bank-to-bank transfers that go through the Automated Clearing House (ACH) Network are becoming increasingly widespread in e-commerce. In 2025 there were 35.2 billion ACH payments with a total value of $93 trillion.

With credit cards carrying significant downsides for both merchants and customers, it’s not surprising that many have turned to ACH payments. They’re accessible to anyone with a bank account, and can be processed for a low flat rate.

In the rush to embrace ACH payments, some have overlooked its hazards, such as the potential for fraud, disputes, and the problems that can arise when a payment fails to go through. Merchants who accept ACH payments should have a plan in place for when payments are returned to the sender, and familiarize themselves with the various ACH return codes that explain why the payment was rejected and how it can be corrected and retried.

What Are ACH Return Codes?

When an ACH payment cannot be completed, the bank that was supposed to receive the payment will send back a return code indicating the reason why it didn’t go through.

ACH payments are carried over a network managed by the National Automated Clearing House Association (NACHA). This organization sets the rules, standards, and terminology for ACH payments, including the return codes.

When a transfer cannot be processed, NACHA requires the receiver’s bank (the Receiving Depository Financial Institution, or RDFI) to send an explanatory return code to the originator's bank (the Originating Depository Financial Institution, or ODFI) within a specified timeframe. For ACH debits in e-commerce, the receiver is the customer and the originator is the merchant.

There are more than eighty different ACH return codes. Each one starts with the letter “R” and is followed by two digits. The ODFI can pass the information from the return code on to their customer, the originator of the transfer, so they can decide whether to try ACH again or use a different payment method.

List of Common ACH Return Codes

Knowledge is power, but memorizing every single ACH return code might be overkill. Here are some of the codes that are most likely to come up in e-commerce.

The following codes must be returned within two business days:

• R01 – Insufficient Funds: The receiver does not have enough money in their account to cover the ACH transfer. The originator can retry up to two times, as a new transaction, within 30 days of the original authorization date.
• R02 – Account Closed: The account is no longer active. The transfer cannot be retried.
• R03 – No Account, or Unable to Locate Account: The account number appears valid but is not associated with the customer name or is not otherwise accessible. If this occurred because the account number was keyed incorrectly, the originator can try again with a new transaction.
• R04 – Invalid Account Number: The account number is structured incorrectly (for example, it may contain the wrong number of digits). The originator needs to obtain the correct account number before retrying the transfer.
• R08 – Payment Stopped: The originator has asked the RDFI to stop the transfer. It can be retried with the originator’s authorization.
• R09 – Uncollected Funds: The receiver does not have sufficient available funds in their account to cover all pending transactions. The originator can retry up to two times, as a new transaction, within 30 days of the original authorization date.
• R16 – Account Frozen: The funds are not available due to legal action or decisions made by the RDFI. The transfer cannot be retried while the account is frozen.

These codes have a 60 calendar day time frame for return. They are used for ACH disputes and other issues that may not be immediately evident:

• R05 – Unauthorized Debit Entry: The account holder has submitted a written statement claiming that the transfer was not authorized. The RDFI will block further transfer attempts against this account until the account holder instructs them to lift the block. The transfer cannot be retried.
• R07 – Authorization Revoked by Customer: The receiver previously gave authorization for ACH transfers, but has since submitted a written statement revoking that authorization. The originator can no longer process transactions to this account and must stop all scheduled payments and recurring billings.
• R10 – Originator is Not Known to Receiver, or Originator is Not Authorized to Debit Receiver’s Account: The receiver does not have a business relationship with the originator, or has not authorized the originator to debit their account. 
• R11 – Entry Not in Accordance with the Terms of the Authorization: The amount was incorrect, the timing of the transfer was outside the authorization date range, or there were issues with the source documents or some other error with the transfer. The originator can correct the information on their end and submit a new entry without needing a new authorization.

What are the Consequences of an ACH Return?

An ACH return code not only means that a payment has failed, it also incurs a fee (usually $2-$5 dollars, charged to the originator in most cases). Like credit card disputes, ACH returns are monitored.

To maintain compliance with NACHA regulations, businesses that process ACH transactions must keep their rates of various return codes under certain thresholds, based on the previous 60 days of activity:

• Overall returns (all codes): 15%.
• Administrative returns (R02, R03, R04): 3%.
• Unauthorized returns (R05, R07, R10, R29, R51): 0.5%

If you believe you have received an ACH return in error, you can contact your bank. In some cases, errors can be resolved and reversed, but there is no equivalent to chargeback representment when it comes to ACH returns. For the most part, returns are final, and if a payment fails and you believe the customer still owes you money, you have to resolve it with them directly.

How to Prevent ACH Returns

Reducing ACH returns requires a combination of strong authorization practices, accurate data handling, and proactive account management. While some returns are unavoidable, many stem from preventable errors or weak controls.

First, merchants must ensure that all payment authorizations are clear, compliant, and well-documented. NACHA rules require proper authorization for every ACH debit, whether written, verbal, or electronic. Using standardized authorization language and retaining records can help prevent unauthorized return codes like R05, R07, and R10.

Second, merchants should focus on data accuracy at the point of entry. Incorrect account or routing numbers are a leading cause of administrative returns (R02–R04). Implement validation tools, such as bank account verification or prenotification (prenotes), to confirm account details before initiating transactions. Even small improvements in data hygiene can significantly reduce return rates.

Monitoring account balance risk is also critical. Returns due to insufficient or uncollected funds (R01, R09) can often be mitigated by timing transactions strategically, such as by aligning debits with known payroll cycles. When a return does occur, follow NACHA guidelines for retries (generally no more than two attempts within 30 days).

Communication plays a key role as well. Providing advance notice of debits, clear billing descriptors, and responsive customer support can reduce disputes and stop-payment requests (R08). Customers are less likely to challenge transactions they recognize and understand.

Finally, track your return rates closely. NACHA enforces thresholds for overall, administrative, and unauthorized returns, and exceeding them can result in penalties or monitoring. Regular reporting allows you to identify trends, isolate problem areas, and take corrective action before issues escalate.

By combining compliance, technology, and customer communication, merchants can materially reduce ACH return rates and maintain a healthier payments operation.

Conclusion

ACH payments can be useful option for merchants to keep in their toolbox, especially for large transactions that would carry hefty fees if carried out by credit card.

Merchants must keep in mind, however, that while the ACH system doesn’t have a dispute mechanism as easy to use (and abuse) as the chargeback process, it does allow account holders to dispute unauthorized transactions.

Effective authentication and fraud detection measures are essential for merchants to conduct bank-to-bank fund transfers safely.