Cards work almost everywhere in Mexico now, but there's one screen you'll see at the till or the cash machine that can quietly cost you 4–8% extra. Knowing how to answer it is the single most useful money skill for a trip south of the border.
The trap is called dynamic currency conversion. When you pay with a foreign-issued card, the terminal or ATM may offer to charge you in dollars, pounds or euros instead of pesos. It sounds convenient, but the merchant's own exchange rate is heavily marked up. Always choose to be charged in Mexican pesos — your own bank's rate will almost certainly be better.
Even then, costs stack up. Banks typically apply a hidden exchange-rate spread of around 2–5% on foreign transactions, and some add a separate foreign transaction fee on top. Cash withdrawals are pricier still: the Mexican ATM operator charges a fixed fee (shown on screen before you confirm), your own bank may add its own charges, and using a credit card for cash usually triggers interest from day one. Check your bank's fee structure before you fly — it varies a lot by account type.
The practical upside is that plastic is genuinely easy to use in Mexico. Visa and MasterCard are accepted almost universally, with American Express and Discover common too, and paper cheques have all but disappeared from shops. Signatures are largely a thing of the past: chip-and-PIN is the norm, and PIN is known locally as your NIP or firma electrónica. Contactless payments via Apple Pay and Google Pay are increasingly accepted at supermarkets, shops and restaurants — and they have a bonus safety angle, since the merchant never sees or touches your card details.
That safety point matters. Card skimming — where the magnetic strip is copied and the CVV recorded — is a known issue in Mexico, as in many countries. If a trader swipes your chip card when they don't need to, be wary. Credit card fraud is usually reimbursable; debit card disputes are harder to win, so many travellers prefer to put purchases on a credit card and use debit sparingly at ATMs.
For a holidaymaker, the takeaway is simple: pay in pesos, decline every on-screen currency conversion, favour chip and contactless over swipes, tell your bank you're travelling, and budget for a few percent in exchange costs no matter what.
