Overseas Supplier Payments: Currency Choice, DCC and FX Fees

When a US or Canadian buyer pays an overseas research supplier, should the charge be taken in the supplier's currency or the buyer's, how do dynamic currency conversion and card foreign-transaction fees differ, and what does EU transparency law require the merchant to show?

When you pay a supplier in another country there are usually two ways to settle the same invoice. You can be charged in the supplier's currency and let your card or bank convert it, or you can accept the merchant's offer to charge you in your own currency at a rate the merchant's payment provider sets. The first is generally the better default. The second is called dynamic currency conversion, and it is worth understanding before you click it.

Neither option removes the card issuer's own foreign-transaction fee, if your card has one. The aim of this article is to separate the three layers of cost, show how to compare them, and set out what a European merchant is required to disclose. It describes the mechanics in general and does not assess any particular provider or product.

Two prices for one order

An invoice in euros from a European supplier is a euro price. If your card is denominated in US or Canadian dollars, a conversion must happen somewhere between the invoice and your statement. The choice at checkout is only about where.

If you pay in the merchant's currency, the merchant is paid in euros and the card network converts the amount to your card currency using its own rate, after which your issuer may add a fee. If you accept conversion at checkout, the merchant's provider converts the amount, shows you a figure in your currency, and charges that. The statement then shows a charge that is already in your currency, and the network does no further conversion.

Dynamic currency conversion: who sets the rate and who earns the margin

Dynamic currency conversion, usually shortened to DCC, is the checkout offer to pay in your home currency. It looks like a convenience, because you see a familiar number. The rate behind that number is set by the merchant's side of the transaction, and a margin is added to the wholesale rate. That margin is shared between the parties who provide the service, not the cardholder.

Card issuers' own consumer guidance tends to point the same way: choose the merchant's currency, because the conversion done by the card network is typically less costly than a rate set at the till or on the checkout page ^[2][3]. That is a general pattern, not a guarantee. The way to know is to compare, which the later sections describe.

The choice should be yours. Card network rules generally require that the cardholder is offered the choice and told the converted amount and rate before agreeing. A checkout that pre-selects your home currency, or presents the choice in a way that hides the exchange rate, is a prompt to stop and read the screen.

Issuer foreign-transaction fees apply either way

Many cards add a foreign-transaction fee, commonly a percentage of the amount, to purchases made abroad or in another currency. Some cards waive it entirely. The cardholder agreement states the rate and the conditions.

The point that surprises buyers is that the fee may still apply when you choose conversion at checkout. Issuers differ in how they classify a transaction. Some look at the currency of the charge. Others look at the country of the merchant or of the merchant's payment provider. A charge made in your own currency to a foreign merchant can therefore still attract the fee, leaving you with the merchant's margin and the issuer's fee together.

What EU Regulation 2019/518 requires an EU merchant to disclose

If the supplier is based in the European Union, a transparency rule applies. Regulation (EU) 2019/518 amended the earlier cross-border payments regulation to cover currency conversion charges on card-based transactions ^[1]. Where a currency conversion service is offered at the point of sale or online, the payer must be told the charges before authorising the payment.

The disclosure is expressed as a percentage mark-up over the latest available euro foreign exchange reference rate issued by the European Central Bank, together with the total amount to be charged in the payer's currency. That gives you a figure you can check against a published rate. Scope, definitions and the exact timing of the disclosure are set by the regulation, so read the text for any case that matters.

The practical use is simple. If a European checkout offers conversion and does not show a mark-up over a reference rate, that is a reason to decline the conversion and pay in euros. If it does show one, you have a number to compare with what your own card would charge.

Wires and FX: a separate fee structure

A bank wire has a different set of charges. The sending bank typically applies its own exchange rate, which contains a margin, plus a fixed fee for the transfer. Intermediary banks on the route may deduct further fees, and the receiving bank may charge to credit the account. The sender can usually choose who bears the charges, as the wire article in this series describes.

The comparison with a card is not obvious in advance, so do it in arithmetic once. For a given invoice, add the wire fee to the converted amount and compare the total with what a card would have cost including its issuer fee. Which is cheaper depends on the order size, because a fixed wire fee is a smaller share of a large order and a larger share of a small one.

Reconciling the statement with the invoice

For a laboratory, the invoice and the statement need to agree in the ledger. Currency conversion is the usual source of a difference, and it is easy to explain if you captured the right figures at the time.

1. Record the invoice amount and its currency, and the date of the order.
2. Record which currency option you selected at checkout and keep a screenshot of the screen that showed the choice.
3. When the charge posts, record the amount in your currency and the posting date, and any separate foreign-transaction fee line.
4. Divide the charged amount by the invoice amount to get the effective rate, and compare it with a published reference rate for the order date.
5. Note the difference in the order record, so the true landed cost of the order is the figure you carry forward.

If the effective rate differs from the reference rate by more than the margin you expected, ask the issuer for a breakdown. If the charge was in a currency you did not select, that is a question for the merchant first and for the issuer second.

What to do next

Read the foreign-transaction line in your card agreement and write down the rate. At the next international checkout, decline conversion unless the screen shows a rate and mark-up you can compare, and save the figures. After two or three orders you will know which option costs less for your card, and you will have the records to show why.