American Express Chargeback Reason Code
American Express Reason Code F24: No Cardmember Authorization
Category FraudBy Payment Defender Editorial TeamUpdated July 17, 2026Last reviewed July 17, 2026
What American Express Reason Code F24 Means
American Express reason code F24 applies when the Cardmember claims they did not authorize or participate in the charge. It is a fraud dispute asserting the transaction was not made by the legitimate Cardmember.
Why This Chargeback Happens
This dispute commonly occurs after true third-party fraud, when a Cardmember does not recognize a charge, or when someone used the Card without permission. Unclear billing descriptors can also prompt this dispute.
What the Cardholder or Issuer Is Claiming
The Cardmember is claiming they did not authorize or participate in the disputed charge.
What Merchants Should Review
Review authentication data, Card-capture method, delivery or service records, and any prior undisputed activity from the same Cardmember. Confirm how the transaction was verified and whether it aligns with legitimate account behavior.
Recommended Chargeback Evidence
- Authorization and verification data for the transaction
- Delivery confirmation or proof of service to the Cardmember
- Evidence of prior undisputed purchases from the same account
- Communication acknowledging the purchase, if available
How to Prevent Similar Disputes
Merchants may reduce these disputes by verifying Cardmembers at purchase, screening high-risk orders, keeping billing descriptors recognizable, and responding quickly to fraud notifications before disputes are filed.
Important Limitations
This page is educational and reflects common industry usage. American Express dispute rules, timelines, and evidence requirements change over time and vary by market and program. Merchants should confirm current requirements with American Express or their processor before responding to any dispute.
Relevant Payment Defender Products
AlertBridge™
AlertBridge™ may help merchants intercept fraud and dispute notifications as alerts before they escalate into chargebacks.
Explore AlertBridge™
Related Reason Codes
Sources and Review Information
- American Express: American Express Merchant Regulations – U.S.
Last reviewed July 17, 2026
Chargeback rules, evidence requirements, and response options may vary by card network, region, processor, and dispute circumstances.