Foreign exchange is one of the most significant costs of an internationally mobile life, yet it receives relatively little attention compared with other financial decisions. The reality is that the difference between using a high-street bank and a specialist currency broker for a single large transfer — a property purchase, for example, or a large pension transfer — can easily amount to £5,000–£20,000 on a £200,000 transaction.
Understanding how the foreign exchange market works, how banks and brokers price their services, and when different solutions are appropriate is genuinely valuable knowledge for any expat or international investor.
How FX rates work
The foreign exchange market is the largest financial market in the world, with daily trading volumes of approximately USD 9.6 trillion (BIS Triennial Survey, April 2025). At its centre is the interbank market — a wholesale market where large banks, central banks, and major financial institutions trade currencies with each other at extremely tight spreads. The rate at the centre of this market — the midpoint between buy and sell prices — is the mid-market rate, often referred to simply as the interbank rate.
The mid-market rate is the rate you see on Google, XE.com, or financial news sites. It is not, however, the rate available to retail customers. Every bank or provider selling currency to a retail customer adds a spread — a markup on top of the mid-market rate — which represents their profit and the cost of providing the service.
Bid/ask spread. A currency quote has two parts: the bid (the price at which the bank buys the base currency from you) and the ask (the price at which the bank sells you the base currency). If GBP/USD is quoted as 1.2500/1.2600, you can sell GBP for USD at 1.2500 or buy GBP with USD at 1.2600. The spread — the difference — is the cost embedded in the transaction. The wider the spread, the more expensive the conversion.
Commissions and fees. In addition to the spread, some banks and providers charge explicit transaction fees — a flat fee per transfer, a percentage commission, or both. These may be disclosed upfront or embedded in the rate.
Bank rates vs specialist broker rates
The most important practical point for expats is that high-street banks offer significantly worse exchange rates than specialist currency brokers, particularly for larger transactions.
A typical high-street bank will add a spread of 2–4% over the mid-market rate. On a £100,000 transfer, this means paying £2,000–£4,000 in excess of the mid-market equivalent — simply through the exchange rate markup, before any fees.
A specialist FX broker typically offers spreads of 0.3–1.5% over the mid-market rate, depending on transaction size and the currency pair. On the same £100,000 transfer, the cost is £300–£1,500. The saving compared with a high-street bank is £500–£3,500 on a single transaction.
For very large transactions — property purchases of £300,000–£1,000,000 or more — the difference is proportionately large. A 2% bank spread vs a 0.5% broker rate on a £500,000 transaction represents a difference of £7,500.
Specialist FX brokers are well-established businesses, regulated by the FCA in the UK, and used routinely by internationally mobile individuals, property buyers, businesses, and financial advisers. Their rates are better not because they are taking more risk, but because they have lower overheads than retail banks and operate at higher volumes in the currency market.
Spot transactions
A spot transaction is a straightforward currency exchange at the current market rate, for settlement typically within two business days. This is the most common type of currency transaction — you want to convert GBP to EUR today at the current rate.
Spot rates fluctuate continuously throughout the trading day (and to a lesser extent overnight) in response to economic news, central bank decisions, geopolitical events, and market sentiment. For amounts under £10,000, the day-to-day rate fluctuation is unlikely to be material enough to time carefully. For larger amounts, rate timing can matter.
Forward contracts
A forward contract allows you to agree an exchange rate today for a transaction that will take place at a future date — typically between one week and two years ahead. The rate is fixed at the time of booking. Settlement — when you actually exchange the currencies — happens on the agreed future date.
Forward contracts are useful in several situations common to expats and international investors:
Property purchase abroad. If you exchange an offer to buy a property at an agreed price in euros, and you need to complete the purchase in three months, a forward contract fixes the sterling cost of the purchase immediately. You eliminate the risk that sterling weakens against the euro between exchange and completion.
Regular salary transfers. If you receive a USD salary and regularly transfer a fixed amount to cover UK commitments — a mortgage, maintenance, school fees — a series of forward contracts can fix the GBP value of those USD transfers for a year ahead, removing monthly exchange rate uncertainty.
Business payment planning. Businesses with predictable foreign currency costs — supplier payments, overseas payroll — use forward contracts to plan their costs with certainty.
Forward contracts are not speculative. You are not betting on rate movements; you are removing uncertainty about the sterling cost of a known foreign currency obligation. The trade-off is that if sterling strengthens, you do not benefit — but you also do not suffer if it weakens.
Currency options
Currency options give you the right — but not the obligation — to exchange currency at a specified rate on or before a specified date, in exchange for paying an upfront premium. Options are less commonly used by private clients than forward contracts because the premium adds cost even if the option is not exercised.
Options can be useful where there is uncertainty about whether a transaction will proceed — for example, if you are in negotiation on a property purchase and not yet certain the deal will complete. A forward contract commits you to the exchange; an option gives you flexibility at a cost.
Large transfer considerations
For transactions above £50,000–£100,000 — property purchases, large investment transfers, pension or lump sum transfers — the following considerations apply:
Use a specialist FX broker, not your bank. The rate improvement on a single large transaction can be thousands of pounds.
Consider fixing the rate in advance. A forward contract on a property purchase eliminates the risk of a rate movement between exchange and completion. The deposit required (typically 5–10% of the amount) is manageable and provides certainty.
Negotiate the rate. Specialist FX brokers will often negotiate the rate for large transactions. The headline rate is a starting point, not a fixed price.
Understand the settlement process. For a property purchase, the transfer must arrive in the right account at the right time for completion. Understand the settlement timescale — SWIFT transfers typically take 1–3 business days — and allow adequate time.
How Global Investments can help
We work with specialist FX brokers and can introduce clients to providers who offer competitive rates for large transactions — property purchases, pension transfers, large investment transfers, and regular international salary or income conversions. We can also advise on whether a forward contract or spot transaction is more appropriate given your specific timing and obligations.
Frequently Asked Questions
What is the difference between the bank rate and the mid-market rate?
The mid-market rate (also called the interbank rate) is the midpoint between the buy and sell price for a currency pair in the wholesale foreign exchange market. It is the rate you typically see on Google or financial news sites. Banks and currency providers add a spread on top of this rate when selling currency to retail customers. The difference between the mid-market rate and the rate your bank offers is effectively a fee. High-street banks typically charge a spread of 2–4%; specialist currency brokers typically charge 0.3–1.5%.
What is a forward contract and should I use one?
A forward contract allows you to fix an exchange rate today for a currency conversion that will take place on a future date — typically between one week and two years ahead. You pay a small deposit (typically 5–10%) and the remainder on settlement. Forward contracts are useful when you have a known future obligation in a foreign currency — such as a property purchase, an ongoing mortgage payment, or a regular salary transfer — and want to remove the uncertainty of rate movements. They are not speculative instruments; they are a planning tool.
What is the bid/ask spread in FX?
When a bank or broker quotes an exchange rate, they quote a buy rate (bid) and a sell rate (ask). The bid is the rate at which they buy the base currency from you; the ask is the rate at which they sell it to you. The difference — the spread — is the broker or bank's profit. For GBP/USD, if the bank quotes 1.2550 bid and 1.2350 ask, the spread is 200 points (or 'pips'). The wider the spread, the more the conversion costs you.
When is it worth using a specialist FX broker instead of a bank?
For transactions over approximately £5,000–£10,000, a specialist FX broker will almost always offer a better rate than a high-street bank. For very large transactions — property purchases, business acquisitions, large investment transfers — the savings can amount to tens of thousands of pounds. For very small transactions (under £1,000), the administrative overhead of using a broker may not be worthwhile, and a digital service like Wise may be more practical.
This guide is for general information only and does not constitute financial advice or a personal recommendation. Banking regulations, tax rules, and product availability change — always verify current rules and seek advice from a qualified independent financial adviser or regulated banking specialist before making any decisions. The value of investments can fall as well as rise and you may get back less than you invest.