Reason code

American Express reason code M38 is used when Amex reverses a previously processed charge for any reason not covered by a more specific code. This could be due to errors in processing, failure to respond to an inquiry, or a determination made by Amex after reviewing the dispute case.

Unlike cardholder-initiated disputes, this type of chargeback is generally triggered by Amex’s internal processes or findings. It may serve as a final action following a failed response, insufficient documentation, or unresolved case details.

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If you believe the reversal was issued in error, review the case and respond with clear, complete documentation:

• Provide all original supporting evidence and note any inconsistencies in Amex’s decision

• If allowed, appeal through your acquirer or dispute management platform

Prevent M38 chargebacks by ensuring every dispute is handled thoroughly and on time:

• Double-check that responses meet Amex’s documentation standards and are submitted before deadlines
  
  
• Keep detailed records of all customer interactions, authorizations, and fulfillment activity
  
  

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