Card application selection is a store-level setting in Adyen that governs how a terminal decides which payment network to use when a shopper's card supports more than one. Adyen handles this automatically in almost every case, but it's worth partners understanding the mechanics, since the terminology comes up in conversations with merchants and in support tickets.

A co-badged card carries more than one payment network on it, usually a local scheme paired with a global one, eftpos + Visa in Australia or Bancontact + Maestro in Belgium are the classic examples. A combo card is one that supports both credit and debit off the same card. US debit cards are their own case, they carry "front-of-card" networks like Visa, Mastercard, or Discover alongside "back-of-card" US debit networks like Accel, NYCE, or PULSE. Each of these networks a card can route through is called an application, and it's the application, not the card itself, that the terminal is choosing between.

First, it checks what's actually available, whether the terminal and the transaction type support a given application, and whether that network is up and running. From there it works through priority rules in order: anything the payment request itself calls for (installments need a credit network, for instance), then any compliance obligation around manual selection, then least cost routing. The whole point is to avoid putting a selection screen in front of the shopper while still routing the transaction somewhere sensible.

Interchange and scheme fees aren't the same across networks, local networks are usually cheaper, though a global network can work out better for certain business types depending on whether fees are flat or percentage-based. This is the main reason a merchant would ever want these rules adjusted, to steer transactions toward whatever network is actually cheaper for their business.

Under EU rules (specifically the IFR Regulation 2015/751, Article 80), a shopper using a co-badged card has to be able to choose which brand to pay with if both are supported, terminals can't just pick silently. In practice that's a Card options button the shopper selects before presenting their card, then they present it, then choose the brand, and may need to present the card again. Skip that flow and the terminal just applies its default. This requirement is EEA-specific, outside the EEA it's less strict, though the general cost and compliance principles still apply. It also depends on the terminal running software version 1.109 or later, older software can't guarantee EEA compliance here.

In the Adyen Customer Area, under the correct merchant account, go to In-person payments > Stores, search for the store, and open it. Under Settings > Payment Features you'll find Card application selection, with two settings:

This is where rules would live that let the terminal choose an application automatically, without prompting the shopper. If more than one rule is active, order matters, Adyen works through them top to bottom so whatever's listed first wins. By default there's nothing configured, you'll see "No active rules" with an Adyen default tag, meaning Adyen's own default logic is doing the deciding.

This toggle decides whether the shopper gets a prompt at all. Off, which is the default, and the shopper can still choose a card brand manually when the terminal offers it. On, and the terminal handles it entirely on its own, no prompt shows up. Since manual selection is a compliance requirement for EEA co-badged cards, this one's really a US-card and combo-debit consideration, not something to flip without knowing which cards it'll touch.

Partners can't edit either setting directly, this isn't self-serve. If a merchant wants their least cost routing priorities adjusted, PIN verification preferences changed, or the frequency of the manual selection screen changed, that's a request to [email protected]. Compliance-dependent rules and anything tied to a required feature can't be changed no matter who asks.