Reason code

American Express reason code M42 is used when a merchant attempts to reverse or refund a transaction, but the request is submitted too late to be processed through standard channels. In these cases, Amex issues a chargeback to return the funds to the cardholder because the merchant's attempt to resolve it fell outside the allowable timeframe.

This can happen when merchants delay refunds, miss internal deadlines, or don’t process credits promptly. Even if the merchant intended to do the right thing, timing is critical—and late action can lead to a chargeback under this code.

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If you submitted the reversal within the allowable window, provide proof of timely action:

• Include timestamps from your refund request, terminal logs, or system confirmation
  
  
• Provide correspondence showing your attempt to resolve the matter promptly
  
  

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Process refunds and reversals quickly to avoid disputes tied to delays:

• Set internal deadlines shorter than Amex’s limits to ensure timely credit submissions
  
  
• Automate refund workflows where possible to reduce manual delays
  
  

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