Reason code

American Express reason code M04 is used when a merchant accepts a transaction that was previously declined by the issuer. This typically happens when a transaction is retried after a decline, and the merchant mistakenly processes the charge without obtaining a valid authorization approval.

Even if the cardholder received the goods or services, the merchant may still be held liable because the transaction lacked a proper authorization. These disputes often result from POS system errors, misunderstanding of decline codes, or manual reattempts without reauthorization.

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If a valid authorization was obtained, provide documentation to show the transaction was approved:

• Submit the authorization code, timestamp, and terminal or gateway logs
  
  
• Include any notes or correspondence explaining how the transaction was reattempted correctly

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Handle declined transactions carefully to avoid unintentional acceptance:

• Never retry a declined card without obtaining a new authorization approval

• Train staff to recognize issuer decline codes and follow proper reattempt procedures