A surcharge cap is an upper limit on the surcharge that a merchant is allowed to add when a customer chooses to pay by card. Caps are set by law, by card network rules, or by both, and they exist to stop merchants from charging more than card acceptance actually costs them.
The approach differs by region. In the United States, where card surcharging is permitted on credit cards in most states, network rules limit the surcharge to the lower of a fixed percentage and the merchant's own cost of acceptance, and some states set their own lower ceilings or ban the practice. Debit cards may not be surcharged. Australia long limited surcharges to the merchant's measured cost of acceptance, and from 1 October 2026 it removed surcharging on eftpos, Mastercard and Visa cards. The European Union and the United Kingdom go further and prohibit surcharges on most consumer cards, which is in effect a cap of zero. A convenience fee is treated under separate rules.