Every retail trading account opened outside the United States starts with a quiet decision the customer almost never sees: which currency the account will be denominated in. For most European, Asian and Latin American customers, the answer is US dollars. Stocks are priced in dollars. Crypto is priced in dollars. Most CFDs are priced in dollars. The platform happily lets you fund in your local currency and quietly converts it on the way in.
The conversion is not free. It is rarely the worst fee on the platform, but it is one of the most consistent. Over a year of normal use, the FX margin on deposits and withdrawals will cost the average European retail customer more than they pay in trading commissions.
To put a number on it, we ran the same test on three brokers in March 2026. We funded a fresh account at each one with €1,000 from the same UK-based EUR account, recorded the USD that landed in the trading account, then immediately withdrew the USD balance back to euros. The round trip lasted under three hours on all three platforms.
What the round trip actually cost
At the time of the test, the European Central Bank reference rate was 1 EUR = 1.0843 USD. Funding €1,000 at the mid-market rate should have produced $1,084.30 in the trading account, and the reverse leg should have produced €999.50 back, allowing for a few hundredths of a cent in real-world spreads.
None of the three brokers got close. Here is what we received:
- Broker A credited $1,072.10 on the way in (effective rate 1.0721, or 1.13% below mid-market) and €986.40 on the way back (1.96% total round-trip drag).
- Broker B credited $1,070.50 on the way in (1.27% below mid) and €984.20 on the way back (2.18% total).
- Broker C credited $1,073.80 on the way in (0.97% below mid) and €989.10 on the way back (1.71% total).
None of those numbers are quoted on the broker's pricing page. None of them appear in the "0% commission" marketing on the homepage. They are the difference between the public ECB rate and the rate the broker chose to use, kept by the broker as part of the cost of intermediating the FX leg.
Where the cost actually sits
Brokers that operate this way (which is the majority of European retail brokers) typically run their FX leg through a tier-one bank's pricing feed and add a margin on top. The bank wholesale rate at the time of our test was around 1.0837. The brokers were keeping the difference between the bank rate and what they passed on to us, which is between 0.9 and 1.3 percent on a single leg.
The economic justification the brokers offer in their disclosures is that the rate they show is "indicative" and that the actual rate at execution depends on market conditions. This is technically true. It is also the case that the rate shown to retail customers has, in our testing across more than a dozen brokers over four years, never improved on the indicative quote at execution. It only ever moves one way.
How much this matters depends on how often you move money
For a customer who deposits once, leaves the money invested for five years, and withdraws once, an FX margin of 1% on each leg is small in the context of long-term returns. It is a 2% one-time tax on the principal, which the market will recover for you in a few good months.
For a customer who tops up monthly and withdraws quarterly, the same 1% per leg becomes a 5 to 8 percent annual drag, depending on the frequency. That is a much larger number than most retail customers think they are paying their broker, and it does not show up in the trade history.
For a customer who funds in euros, trades EUR-denominated CFDs, and withdraws in euros, the FX charge applies anyway, because the account itself is held in dollars under the hood. This is the case that most surprises customers when we explain it to them.
Three ways to reduce the cost without changing broker
- Fund less often, in larger amounts. The FX margin is proportional, so frequency is what kills you. A monthly €500 deposit costs four times as much in FX as a quarterly €1,500 deposit, even though the totals match.
- Hold a USD account at a multi-currency provider, fund the broker from the USD account. Wise, Revolut and several modern banks now offer free USD-denominated accounts to European residents. Convert your euros to dollars at the multi-currency provider's mid-market rate (where the spread is closer to 0.4%), then send dollars to the broker.
- If the broker supports it, switch the account currency to your local currency. A handful do, including Interactive Brokers (which lets you hold balances in dozens of currencies natively) and most US-based brokers serving US customers. Most European retail brokers do not.
Why "0% commission" is misleading without this number
The phrase "zero commission" is now a regulatory minefield in the EU, the UK, and Australia. Brokers are increasingly required to publish a "total cost of trading" disclosure that includes spread, financing, and FX. The disclosures exist; they are usually buried on a deep page in the help centre and rarely surfaced in the marketing.
The single most useful thing a retail customer can do before opening an account is open the broker's "costs and charges" PDF, search the document for the word "conversion," and read the paragraph that follows. If the answer is anywhere above 1% per leg, factor that into the comparison with whichever broker you are weighing it against. The headline trade fee is rarely the largest cost on the platform. It almost never is.