Network
American ExpressCode
F24Response window
20 calendar daysWin difficulty
HardDispute type
FraudAmex F24 — No Cardmember Authorization: What It Is and How to Respond
Act immediately. Amex gives you only 20 calendar days to respond — 10 fewer than Visa. By the time you receive the notification, you may have fewer than 2 weeks. Treat every F24 dispute as a day-1 priority.
Amex F24 is American Express's fraud dispute code for card-not-present transactions. It's the Amex equivalent of Visa 10.4 and Mastercard 4837 — the cardmember (Amex calls cardholders "cardmembers") is claiming a transaction was made without their authorisation. This covers online fraud, phone orders, and any card-absent transaction where the cardmember says they didn't make the purchase.
What makes F24 different from Visa and Mastercard fraud disputes isn't the evidence — it's everything else. American Express operates as both the issuing bank and the card network for most of its cards. This means Amex investigates and decides disputes directly, not through a separate issuing bank. The 20-day response window is strictly enforced. And the dispute submission process goes through American Express Merchant Services, not through your standard processor chargeback interface.
How Amex disputes differ from Visa and Mastercard
20-day response window
Only 20 calendar days from the notification date. Visa and Mastercard give 30 and 45 days respectively. This is not a soft deadline — missing it means an automatic loss.
Amex is issuer AND network
There's no separate issuing bank to arbitrate. Amex investigates, decides, and executes the dispute outcome. This makes the investigation process faster but less predictable.
Different submission channel
Amex disputes are handled through American Express Merchant Services (not through your payment processor's standard dispute interface in most cases). Check whether your processor routes Amex disputes through their dashboard or requires you to go to the Amex Merchant website directly.
Full Recourse (FR2) programme
If your merchant account is enrolled in Amex's FR2 programme, you cannot dispute F24 chargebacks regardless of evidence. Check your Amex merchant agreement before building a response — if you're on FR2, accept the chargeback immediately.
Common reasons you received this dispute
- 1A fraudster used stolen Amex card details to make a purchase on your store
- 2The cardmember made the purchase but doesn't recognise the billing descriptor
- 3A household member used the primary cardmember's card without explicit permission
- 4The cardmember authorised the purchase but later disputed it as fraud
- 5No CVV or billing address verification was performed at checkout
- 6The transaction was processed after the card was reported lost or stolen to Amex
Can you win this dispute?
Fight this dispute if...
- ✓You have SafeKey / American Express 3DS authentication with a successful result — liability shifts to Amex
- ✓CVV matched and billing address verification (AVS) returned a positive result
- ✓You can demonstrate a prior service relationship with the cardmember (prior orders, account history)
- ✓Your billing descriptor clearly and recognisably matches your store name
- ✓The delivery was confirmed by carrier to the billing address
Accept this chargeback if...
- ✗Your merchant account is enrolled in Amex's Full Recourse (FR2) programme — you cannot contest F24 under FR2
- ✗No SafeKey/3DS authentication was performed
- ✗No CVV or AVS verification on record
- ✗No connection between the device, IP, or email and any prior legitimate transaction
- ✗The transaction value doesn't justify the investigation time
Evidence checklist
- ✅ Required
SafeKey / Amex 3DS authentication result: If enabled, this is your strongest protection. The authentication record from your processor showing a successful ECI and CAVV/AAV. When authentication succeeds with Amex, liability shifts away from you.
- ✅ Required
Order confirmation with full transaction metadata: IP address, email, billing and shipping addresses, device type, and exact checkout timestamp.
- ✅ Required
CVV and AVS match results at authorisation: The processor response codes. Even a partial AVS match (postal code only) is worth including.
- ⭐ Strongly recommended
Carrier delivery confirmation: Delivery to the billing address with timestamp. Establishes a link between the transaction and the cardmember's address.
- ⭐ Strongly recommended
Prior order history from same cardmember: Amex has no CE 3.0 equivalent, but prior order history showing a relationship with this cardmember is relevant supporting evidence.
- ⭐ Strongly recommended
Billing descriptor documentation: Screenshot showing exactly how the charge appears on an Amex statement.
- ○ If available
Device fingerprint and IP geolocation: Supporting evidence linking the checkout device to the cardmember's location.
- ○ If available
Customer account login history: Prior logins from the same device demonstrate an established account relationship.
How to submit your Amex response
Amex disputes come through American Express Merchant Services. Most mid-size processors (Stripe, PayPal, Adyen) route Amex chargebacks through their standard dispute interface. Smaller processors may require you to log in to the Amex Merchant Center directly. Check with your processor on day 1 — not knowing where to submit can cost you the deadline.
The Amex merchant portal has structured evidence fields similar to Stripe's. Upload each exhibit as a separate file, label them clearly (Exhibit A, Exhibit B), and reference each in your written response.
Amex's investigation team tends to be detailed. A well-organised response with clearly labelled exhibits and a concise letter performs better than a long, disorganised submission.
"We are writing to dispute chargeback [reference] under American Express dispute code F24. The transaction was authenticated via American Express SafeKey on [date] at [time], with ECI code [X] and valid CAVV. Authentication was successful, and under American Express's liability shift rules, responsibility for this fraud claim rests with American Express, not the merchant. We have attached the full SafeKey authentication record (Exhibit A), the complete order confirmation including IP address and device details (Exhibit B), and the carrier delivery confirmation (Exhibit C). We respectfully request reversal of this chargeback."
Key deadlines
Response window: 20 calendar days from the notification date — the shortest major network deadline.
Missing the deadline means an automatic loss with no exception.
Pre-arbitration: if Amex rejects your response, you have limited escalation options — Amex's dual role as issuer and network reduces the impartiality of the arbitration process.
Practise good calendar hygiene: log F24 notifications immediately with a response-due date, and set a reminder 5 days before the deadline.
How to prevent this chargeback
- 1
Enable American Express SafeKey (3DS2): SafeKey is Amex's 3DS implementation. Authenticated transactions shift fraud liability to Amex. Enable it through your payment processor — most modern processors support SafeKey alongside Visa Secure and Mastercard Identity Check.
- 2
Fix your billing descriptor for Amex transactions: American Express cardmembers call Amex customer service to dispute charges, and Amex agents specifically look for descriptor clarity. A descriptor that doesn't clearly match your brand generates F24 disputes even from legitimate customers. Audit your descriptor in your processor's settings.
- 3
Verify CVV and billing address on every Amex transaction: Amex's fraud tools are sophisticated — transactions with CVV mismatches and AVS failures are flagged in their monitoring systems. Decline these at checkout. Not doing so reduces your defence options significantly.
- 4
Send order confirmation emails immediately: With a clear description of what was purchased, the exact amount, and the billing descriptor text. This addresses "I don't recognise this charge" F24 disputes from cardmembers who forgot or confused a legitimate purchase.
- 5
Check your FR2 enrolment status: American Express's Full Recourse programme removes your right to contest F24 chargebacks entirely. If you're enrolled and don't know it, you'll build dispute responses you can never submit. Check your Amex merchant agreement or contact Amex Merchant Services to confirm your status.
Frequently asked questions
What is an Amex F24 chargeback?
Amex F24 is filed when an American Express cardmember claims a card-not-present transaction was unauthorised. It's Amex's equivalent of Visa 10.4 — a fraud dispute for online and phone orders. The key difference is the 20-day response window, which is shorter than Visa (30 days) and Mastercard (45 days).
Why is the Amex response deadline shorter than Visa or Mastercard?
American Express operates as both the issuing bank and the card network for most Amex cards, which gives it more direct control over the dispute timeline. The 20-day window is a fixed policy. There is no extension process — treat every F24 as a day-1 priority.
What is Amex Full Recourse (FR2) and does it affect F24 disputes?
Full Recourse is an Amex programme under which merchants agree to accept certain chargeback types without contest in exchange for other processing benefits. If your merchant account is enrolled in FR2, you cannot dispute F24 chargebacks regardless of evidence. Check your Amex merchant agreement before building a response — contesting an FR2-enrolled F24 is procedurally invalid.
Can I win an Amex F24 dispute without SafeKey authentication?
Yes, but it's harder than with Visa, which has CE 3.0 as a fallback. Amex has no prior-transaction liability shift mechanism. Your best evidence without SafeKey is CVV and AVS match results, delivery confirmation to the billing address, and prior order history demonstrating an established relationship with the cardmember.
Related reason codes
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