DCC, explained properly

Local currency, virtually always. Choosing your home currency is what activates DCC. Paying in local currency routes the conversion through your card network at close to the mid-market rate.

The one theoretical exception (an issuer that waives its foreign fee for home-currency billing, combined with an unusually low DCC markup) is rare enough that the calculator treats it as a special case you must switch on deliberately.

Field tests, kept apart rather than averaged: 2.6% to 12% at ATMs across 13 countries (BEUC’s 2017 paper, reporting Stiftung Warentest’s 2016 test), usually more than 5% and peaking at 13.7% (Stiftung Warentest, 2019), and 6.51% to 19.00% across ten Prague operators (Měšec.cz, April 2026). Treat 13.7% as a 2019 ceiling, not a current one. Each measurement with its sample and benchmark.

Concretely: withdraw €200 and accept a rate of $1.18 per euro when the market says $1.10, and you hand over about $16, a 7.3% tip to a machine.

Because it earns money for everyone except you. The DCC provider takes a cut of the markup and rebates part of it to the merchant or ATM operator as commission. The service is packaged as transparency (“know exactly what you’ll pay”), which is why the offer screens feel so reassuring while costing you several percent.

Yes. Declining DCC never cancels the withdrawal; it only changes who converts. Machines word the screens to make you doubt this; some show DECLINE in grey next to a bright green ACCEPT. The grey button works fine.

Before PIN or signature: ask them to cancel and re-run in local currency. After the fact: ask for a reversal, and keep the receipt. Card-network rules require that DCC be the cardholder’s choice, so a receipt showing you weren’t given one is solid ground for a dispute with your issuer.

Marketing for DCC. The only thing guaranteed is the markup, locked in immediately. The network rate you get by declining is set at settlement, so it isn’t knowable to the penny in advance, but it is reliably several percent better. Volatile-currency destinations lean on this pitch hardest.

Your card network (Visa or Mastercard) converts at its published wholesale rate, typically within a fraction of a percent of the ECB reference, and then your issuer adds its foreign fee, if it has one. Both networks publish rate lookup tools, with one catch worth knowing: the rate that applied is the one for the date your transaction was processed, which is often not the date you paid. Looking up the wrong date is a common way to conclude you were cheated when you were not.

Sometimes, for two separate reasons that get blurred together. Your rate is set when the transaction is processed, not when you tap, and the ECB publishes reference rates on working days only, so a weekend payment is exposed to whatever the market does across the gap. Separately, some card issuers apply their own explicit weekend markup, which is a fee they choose rather than anything the networks impose. Either way it is small next to a conversion markup, and never a reason to accept one.

Legal, but regulated. Network rules require DCC to be offered as a genuine choice, with the rate and markup disclosed. In the EU, the disclosure duty introduced by Regulation (EU) 2019/518 now sits in Article 4 of Regulation (EU) 2021/1230, and has applied to ATMs and card terminals since 19 April 2020. It caps nothing; it makes the cost visible. Read that line.

Two limits matter more than the rule itself. It covers payments denominated in euro or another EU member state currency, so it does nothing for a euro cardholder in Bangkok or New York, and it is written for ATMs and points of sale rather than for foreign websites. Where the disclosure rule actually reaches goes through both.

Visa and Mastercard both permit DCC under consent-and-disclosure rules, so the refusal habit is identical on either. Amex is more often asserted than checked: the common claim that American Express bans DCC network-wide is not something Amex itself publishes, and Amex warns its own cardholders about third-party conversion rather than promising to block it. What is documented is narrower and product-level. Which cards can and cannot be offered a conversion sets out what is actually verifiable.

DCC works identically on business cards, and the stakes are often higher: travel-heavy teams accepting DCC by default can quietly lose several percent of their entire T&E spend. Same fix: pay local, and put it in the expense policy.