Why it matters

A visitor from another country pays by card. Without DCC, the merchant charges in its own currency and the card network converts the amount for the issuer, which may add a fee. The cardholder learns the exact amount from their statement.

With dynamic currency conversion, the terminal, the ATM or the checkout page offers to charge the card in the cardholder's own currency, right now, at a rate the merchant's DCC provider sets:

• the cardholder sees the final amount in their currency at once, and usually pays a margin for that certainty;
• the merchant and the acquirer earn part of the margin, which is why DCC is common in hotels, shops, restaurants and ATMs that serve travellers;
• the networks allow DCC only under strict rules ⚠: the choice must be the cardholder's, the offer must show the amounts, the rate and the markup, and the receipt must say what was chosen.

A terminal that gets these rules wrong exposes the acquirer to chargebacks and penalties. For a developer or tester, DCC touches almost every layer: the BIN table, the rate file, the cardholder screen, the EMV kernel, the authorisation and clearing amounts, refunds and receipts.