Foreign Currency Capital Gains: UK Tax Rules for 2026/27

Why Foreign Currency Is a Taxable Asset

Many people are surprised to learn that holding foreign currency can create a UK tax liability. When you buy US dollars, euros, or any other currency and later convert them back -- or spend them -- you may have made a taxable disposal for capital gains tax (CGT) purposes.

HMRC treats foreign currency held by UK residents as a chargeable asset. Any gain made between the date of acquisition (when you bought the currency) and the date of disposal (when you converted, spent, or transferred it) is potentially subject to CGT.

This applies across a wide range of scenarios:

• Converting foreign currency back to sterling after a holiday (where significant sums are involved)
• Holding euros or dollars in an overseas bank account that has grown in sterling value due to exchange rate movements
• Receiving salary in a foreign currency and converting it later
• Holding proceeds from a property sale abroad in the local currency before repatriating

The rules can catch people unaware, particularly those who hold foreign currency accounts, receive income or dividends in foreign currencies, or have sold overseas property and left proceeds offshore.

What Counts as a Disposal?

A disposal occurs whenever you cease to hold foreign currency or exchange it for something else. Common disposals include:

• Converting foreign currency to sterling -- the most obvious disposal
• Using foreign currency to buy another currency -- for example, converting euros to US dollars
• Spending foreign currency -- each purchase abroad is technically a disposal of the currency at the point of spending
• Transferring foreign currency between accounts in some circumstances

The gain or loss is calculated as the difference between the sterling value at the date of acquisition and the sterling value at the date of disposal.

Private Use Exemption

There is a limited exemption for foreign currency acquired and spent for personal use on a trip abroad. Where currency is bought specifically for a holiday or personal trip and is spent on that trip (or converted back promptly afterwards), HMRC accepts that this is private use and no CGT applies.

However, this exemption does not extend to holding foreign currency as an investment, maintaining large foreign currency balances for significant periods, or speculative currency trading.

Sterling Conversion: Which Exchange Rate to Use?

One of the most practically important questions in calculating a foreign currency gain is: what exchange rate do I use?

HMRC requires all amounts to be converted to sterling at the exchange rate applicable on the date of the transaction. You have two main options:

Option 1: HMRC Published Exchange Rates

HMRC publishes average monthly and annual exchange rates for most major currencies. These are available on the GOV.UK website and are updated regularly. Using these official rates is safe and accepted by HMRC, and they are usually the most practical option for individuals with multiple transactions.

For income tax purposes (for example, converting foreign employment income), you would use the rate for the month the income was received. For CGT purposes, you would use the rate for the month of acquisition and the month of disposal.

Option 2: Spot Rate on the Transaction Date

You can also use the actual spot rate on the specific date of each transaction. This may produce a more accurate result if exchange rates moved significantly during the month. You should be able to obtain this from your bank statement, an authorised exchange provider, or a financial data source.

Whichever approach you choose, be consistent. HMRC expects you to apply the same methodology to both the acquisition cost and the disposal proceeds. Switching rates to produce a more favourable outcome would be viewed very unfavourably by HMRC.

Calculating a Foreign Currency Gain: Step by Step

Here is a worked example using US dollars:

Acquisition: In January 2025, you buy USD 50,000 when the exchange rate is USD 1.25 to GBP 1. Your sterling cost is GBP 40,000.

Disposal: In March 2026, you convert the USD 50,000 back to sterling when the rate is USD 1.10 to GBP 1. Your proceeds are GBP 45,455.

Gain: GBP 45,455 minus GBP 40,000 = GBP 5,455 gain.

In 2026/27, the CGT annual exempt amount is GBP 3,000. Your gain of GBP 5,455 exceeds this, so the excess of GBP 2,455 is subject to CGT.

As a basic rate taxpayer, you would pay CGT at 10% on other assets (GBP 246). As a higher or additional rate taxpayer, the rate is 20% (GBP 491). Foreign currency gains are treated as 'other assets', not residential property, so the lower CGT rates apply.

Foreign Currency Bank Accounts: The Special Pooling Rule

Ordinary CGT pooling rules (which combine all shares in a company into a single pool) do not work neatly for foreign currency, because each transaction involves a different amount with a different rate. HMRC therefore applies a single account rule for foreign currency held in a bank account.

Under this approach, all amounts of the same currency held in the same account are treated as a single pool. When you withdraw or dispose of currency, you calculate the average acquisition cost of the currency in the pool at that time and compare it to the disposal proceeds.

This is important for individuals who make multiple deposits and withdrawals of the same foreign currency. Rather than tracking each individual transaction, the pool tracks the cumulative position.

Example: You hold a euro account. You deposit EUR 10,000 in January at GBP 0.85 per euro (cost GBP 8,500) and EUR 5,000 in June at GBP 0.88 per euro (cost GBP 4,400). Your total pool is EUR 15,000 at an average cost of GBP 12,900 (GBP 0.86 per euro). If you withdraw EUR 6,000 in December when the rate is GBP 0.90 per euro, your proceeds are GBP 5,400. The cost attributable to EUR 6,000 from the pool is GBP 6,000 x 0.86 = GBP 5,160. Gain: GBP 240.

Cryptocurrency: A Common Confusion

A frequent question is whether cryptocurrency should be treated the same as foreign currency. The answer is no.

HMRC published comprehensive guidance in 2019 and has since updated it to confirm that cryptocurrencies such as Bitcoin and Ethereum are cryptoassets, not foreign currency. HMRC does not consider them to be money or currency.

The practical difference is significant:

• Cryptocurrency is pooled using the same share identification rules as equities (using a 'Section 104 pool', plus same-day and bed-and-breakfast matching rules).
• There is no private use exemption for spending cryptocurrency on personal items.
• Every disposal -- including using crypto to buy goods or services -- is a CGT event.
• Converting one cryptocurrency to another is a disposal for CGT purposes.

The CGT annual exempt amount of GBP 3,000 applies to crypto gains in the same way as other assets. However, the detailed calculation methodology differs from foreign currency, so the two should not be conflated.

Foreign Currency Income: Different Rules Apply

It is important to distinguish between capital gains on foreign currency and income received in foreign currency. If you receive salary, rental income, dividends, or self-employment income in a foreign currency, the income itself is subject to income tax, not CGT.

The conversion to sterling for income tax purposes should be done at the rate on the date the income arose (or HMRC's average rate for the period). Any subsequent gain or loss on holding the currency before converting it to sterling would then be a capital gain on the currency holding itself.

For example, if you are paid USD 10,000 in January and do not convert it to sterling until July, you have:

1. Employment income assessed in January (converted at January rate) -- taxed as income.
2. A CGT position on the currency itself from January to July -- the gain or loss on the exchange rate movement during that period is a capital matter.

Reporting Foreign Currency Gains to HMRC

Foreign currency gains are reported through Self Assessment. If your total gains in the tax year exceed the annual exempt amount (GBP 3,000 in 2026/27), or your total proceeds exceed four times the annual exempt amount (GBP 12,000), you must complete the Capital Gains supplementary pages (SA108) of your Self Assessment return.

Even if your gains are below the threshold, it is good practice to report them, as HMRC may question large disposals that do not appear on a return.

Real-Time Capital Gains Service

If you do not normally complete a Self Assessment return, you can report and pay CGT on certain other assets using HMRC's Real-Time Capital Gains Service (accessible via your Personal Tax Account). This is typically used for residential property but can also be used for other assets including foreign currency.

Currency Losses and Offsetting

If you have made a loss on a foreign currency disposal -- for example, you sold dollars at a rate lower than when you bought them -- you can offset that loss against other capital gains in the same year, or carry it forward to offset against future gains.

Currency losses must be reported to HMRC within four years of the end of the tax year in which they arose, or they may be lost. You cannot simply offset them informally without making a claim.

Practical Steps for UK Holders of Foreign Currency

Keep records of every acquisition and disposal. Note the date, the amount, and the exchange rate. Bank statements can help but are not always sufficient if multiple currencies are involved.

Calculate gains and losses at the end of each tax year. Currency movements can be unpredictable, and gains may arise without you actively doing anything beyond holding the balance.

Use HMRC's average exchange rates where possible. They simplify the calculation and are accepted by HMRC.

Do not assume small gains are below the threshold. The GBP 3,000 annual exempt amount applies across all your capital assets, not just foreign currency. If you have also sold shares or a second property, your exempt amount may already be used up.

Consider taking professional advice if you hold large balances in foreign currency, have complex multi-currency portfolios, or are repatriating significant overseas funds.

Summary

Foreign currency held by UK residents is a chargeable capital asset. Gains arise when the sterling value of the currency increases between acquisition and disposal. HMRC requires conversion to sterling using published or spot exchange rates, applied consistently to both cost and proceeds. The CGT annual exempt amount of GBP 3,000 applies in 2026/27. Foreign currency bank accounts use a single pool approach. Cryptocurrency is explicitly excluded from foreign currency treatment and follows separate cryptoasset rules. Gains above the exempt amount must be reported via Self Assessment or HMRC's Real-Time CGT Service.