At year end, many UK businesses selling internationally discover that their cross-border margins sit several points below domestic ones. The cause is rarely pricing or shipping. It is hidden foreign exchange costs — markups applied at checkout, settlement and payout that never appear as a separate line item. According to Bibby Financial Services’ Trading Places report, UK SMEs lost an average of £53,000 each to currency volatility across 2024–25. For sellers operating across multiple markets, multi currency payment processing is not simply a checkout feature — it is a margin-protection strategy. This guide explains where FX costs hide in the payment journey and how transparent processing closes the leak.

FX leakage rarely comes from a single source. It compounds across three stages of every international transaction, and because each markup is embedded rather than itemised, most sellers never see the full cost.

When a customer pays in their local currency and the transaction is converted to GBP at point of sale, the applied rate is typically marked up 1–3% above the mid-market rate. This markup is invisible to both the customer and the merchant.

The timing and exchange rate used to convert international revenue into GBP determine how much actually reaches the merchant account. A marked-up rate applied at the wrong moment compounds the checkout loss.

Paying international suppliers or partners applies the same markup in reverse. Revenue converted from EUR to GBP at one margin, then converted back to EUR for a supplier payment at another, creates a round-trip cost that doubles the leakage on a single transaction cycle.

The Bibby Financial Services survey of over 500 UK SME decision-makers found that 54% of businesses trading overseas reported losses from FX volatility — a figure that rose to 65% among service-sector firms. Most of this cost is only discovered when someone looks deliberately.

A properly configured multi-currency payment gateway addresses each of these leakage points by giving the seller control over when, whether and at what rate conversion happens.

Like-for-like settlement means collecting revenue in a currency and settling in that same currency, avoiding forced per-transaction conversion. A UK seller receiving EUR payments can hold that revenue in a EUR balance, use it to pay EUR-denominated costs directly, or convert to GBP at a favourable moment. This is the single most effective structural defence against FX leakage for businesses with consistent multi-currency revenue.

Holding balances in the currencies you trade in — GBP, EUR, USD and others — allows a business to collect and pay in each currency without round-tripping through sterling. Conversion becomes a deliberate treasury decision made at a chosen rate and amount, rather than an automatic per-transaction cost applied by the payment provider.

The critical question for any provider is straightforward: what is your FX margin above mid-market, and is it disclosed per transaction? An embedded all-in rate makes FX cost invisible and unmanageable. Transparent pricing — where the mid-market rate and the provider’s margin are shown separately — allows a finance team to measure, compare and control the cost of every conversion.

When evaluating an international payment solution, these capabilities separate margin-protective processing from standard payment acceptance:

ONERWAY’s payment platform enables UK businesses to accept payments globally across 80+ currencies with transparent FX pricing, like-for-like settlement and unified pay-in and payout infrastructure — so conversion is controlled by the business, not absorbed as a hidden cost.

Hidden FX costs quietly erode international margins at every stage of the payment journey — checkout, settlement and payout. For UK sellers operating across multiple markets, the defence is not better negotiation on individual transaction fees but a structural shift: multi-currency processing with transparent pricing and like-for-like settlement that turns conversion from an automatic cost into a controlled decision.

If you suspect FX is eating into your margins, ONERWAY’s UK team can run an FX exposure review to show exactly where conversion costs sit in your payment flow. Get in touch.

Like-for-like settlement means settling in the same currency that was collected, avoiding forced per-transaction conversion to GBP. This removes the marked-up exchange rate that would otherwise be applied automatically, keeping more of each international sale intact.

Use a payment gateway that offers transparent FX pricing with disclosed margins, multi-currency accounts that hold balances in the currencies you trade in, and the ability to convert deliberately at a chosen rate rather than automatically on every transaction.

Holding balances in the currencies you regularly collect and pay in avoids the cost of converting to GBP and back again. Converting deliberately when the rate is favourable, rather than automatically on each transaction, reduces total FX spend.

The mid-market rate is the real interbank exchange rate at which banks trade currencies with each other. The actual FX cost to a business is the margin a provider adds above this rate. If that margin is not disclosed, the cost is invisible and unmanageable.

Multi-currency payment processing is the ability to accept, hold and settle payments in multiple currencies so a business can trade internationally without round-tripping every transaction through GBP. It gives sellers control over when and at what rate currency conversion happens.

ONERWAY’s multi-currency payment processing lets UK businesses accept payments across 80+ currencies with transparent FX pricing and like-for-like settlement — protecting margin from the hidden conversion costs that quietly erode international profitability. If you suspect FX is eating into your margins, our UK team can run an FX exposure review. Get in touch.