Reason code

American Express reason code M01 is used when Amex authorizes a chargeback due to a merchant’s failure to comply with transaction processing requirements. This is a broad code that often results from technical issues, policy violations, or procedural errors that prevent a valid response from being reviewed or accepted.

Unlike cardholder-initiated disputes, this chargeback can stem from issues such as incorrect documentation formatting, unauthorized adjustments, or settlement errors. Even if the transaction itself was legitimate, the merchant’s misstep in handling the dispute or processing flow can lead to a chargeback under this code.

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If the chargeback was issued in error, gather documentation to support proper compliance and resubmit if permitted:

• Provide transaction logs, policies, and evidence that all Amex requirements were followed
  
  
• Include correspondence or technical records showing the error was not on your side
  
  

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Prevent authorization-related chargebacks with tight processing discipline and documentation accuracy:

• Ensure your team understands Amex processing requirements and formatting rules
  
  
• Review each transaction and dispute submission for completeness and compliance before sending

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