Processing Errors
M39 Correct a Previous Transaction
Details
American Express reason code M39 is used when Amex reverses or adjusts a transaction to correct an error from a prior charge. This could include fixing a misprocessed refund, double billing, or any transaction where a correction was necessary but not handled properly by the merchant.
This code is typically not cardholder-initiated—it’s triggered by Amex when their systems or investigations determine that a previous transaction was not settled correctly. If the merchant failed to resolve the issue on their own, Amex may process a chargeback to enforce the correction.
Timing to raise the dispute (Issuer/Cardholder)
Timing to respond to the dispute (Acquirer/Merchant)
How to respond?
If you’ve already resolved the issue or believe the correction was inaccurate, submit evidence to clarify the transaction history:
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Provide receipts, refund records, or transaction logs showing the matter was properly addressed
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Include any customer communications confirming resolution or agreement
How to prevent?
Be proactive in correcting transaction errors before they escalate into disputes:
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Monitor your transaction logs and refund activity regularly for inconsistencies
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Respond quickly to cardholder inquiries to resolve issues without Amex intervention