What American Express C18 means
This code covers reservation cancellations and advance deposits under Amex's Assured Reservation and CARDeposit programs: the Card Member says they canceled in time or expected a deposit refund.
Common causes
- Cancellation logged but not processed before the no-show charge ran
- Cancellation outside the policy deadline that the guest did not understand
- Missing cancellation number in the property management system
Evidence that answers it
- Reservation confirmation showing the cancellation policy and deadline
- Property records showing no cancellation number was issued, or that cancellation came after the deadline
- Proof of credit if the deposit was refunded
How to prevent it
- Issue and log a cancellation number for every cancellation, as Amex's programs require
- State the no-show and deposit policy at booking and in the confirmation
- Process cancellation credits the same day
How Verdikx helps with C18
C18 is rare for e-commerce stores. Where it appears, Verdikx applies its canceled playbook, which asks for the disclosed policy, the cancellation timeline and any credit already issued, and drafts a response for you to review.
Frequently asked questions
What does American Express reason code C18 mean?
Amex C18 means the Card Member says they canceled a lodging reservation, or a CARDeposit (advance deposit) credit never arrived, but they were billed a no-show or deposit charge. It mostly affects hotels and rentals. Win with documentation that the no-show or deposit charge was valid under disclosed terms, or proof of credit.
Is American Express C18 worth fighting?
Our reference rates C18 ("No Show" or CARDeposit Canceled) sometimes winnable, depending on the evidence you have. The evidence that answers it starts with reservation confirmation showing the cancellation policy and deadline. The cardholder's bank decides the outcome.
How long does a cardholder have to file a American Express C18 chargeback?
Usually 120 days from the transaction date, under the network's issuer time limits for most codes. Your processor gives you far less time to respond, so work from the due date on the case.
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Sources
- American Express: How to Manage and Help Prevent Disputes (US reference guide, version 2024PROP) (checked October 5, 2026)
Last reviewed by Verdikx Research.