Reason code

American Express reason code 173 is issued when a cardholder believes they were charged more than once for a single purchase. This often happens due to technical issues during checkout, manual entry errors, or confusion when a transaction is reattempted.

In many cases, one of the transactions may have been authorized but not captured—or reversed before settlement. These disputes usually stem from a lack of clarity in the billing history, and they can often be resolved with clear documentation from the merchant.

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If the transactions were not duplicates, show that each charge was valid and distinct:

• Provide unique receipts, signed orders, or shipping confirmations for each transaction

• Include transaction timestamps or authorization logs showing separate purchases

Put systems in place to avoid accidental double charges and reassure customers at checkout:

• Configure your payment system to detect and block duplicate authorizations

• Clearly communicate to customers when a transaction is retried or reversed