How Stablecoins Are Taxed in the UK: CGT and FX Explained

Stablecoins are often seen as the safe harbour of the crypto world. Investors treat them as a digital version of cash, moving in and out of tokens like USDT or USDC when they want to step away from volatility.

Stablecoins are also very much in the news right now, with Tether announcing plans to launch a new stablecoin, USAT, and the Bank of England proposing limits on how much stablecoin an individual investor can hold.

With stablecoins becoming more widely used, an important question follows: how does HMRC actually treat them for tax purposes?

In this article we explain why stablecoins are not the same as holding US dollars in a bank account, how they can still trigger capital gains or losses on foreign currency movements, and what you need to record for your tax return.

Contents

• 1. How HMRC Views Stablecoins
• 2. How Exchange Rates Create Gains and Losses
• 3. Record Keeping
• 4. HMRC Consultation on Stablecoins
• Conclusion

1. Stablecoins and HMRC

Stablecoins are designed to track the value of another asset, usually the US dollar. Tokens like USDT, USDC, and Tether’s proposed USAT are all pegged to the dollar and are often treated by investors as a digital version of cash.

From HMRC’s perspective, however, stablecoins are cryptoassets, not currency. Transactions involving stablecoins fall within Capital Gains Tax (CGT) rules, just like any other cryptoasset.

Swapping crypto into a stablecoin is a taxable disposal for UK Capital Gains Tax purposes. The same applies when you swap out of a stablecoin into another cryptoasset or convert it into GBP. This means that swapping ETH into USDT, or cashing out of USDT into GBP, are disposals in the same way as any other crypto transaction. The gain or loss is measured using the pound sterling value at the time of each transaction.

Example: Swapping ETH to USDT and then to GBP
Dani owns 2 ETH which originally cost her £3,000. She decides to convert her ETH into USDT and receives 4,500 USDT, worth £3,300 at the time of the swap.

For Capital Gains Tax purposes, Dani crystallises a gain of £300, being the market value of her disposal proceeds (£3,300) less her acquisition cost (£3,000).

Later, Dani cashes out her 4,500 USDT into GBP and receives £3,500. On this second disposal, she recognises a further gain of £200, calculated as the proceeds (£3,500) less the market value of the USDT at the time she acquired them (£3,300).

Although stablecoins are often used as a way to “step out” of the market, for tax purposes they are treated in the same way as any other cryptoasset.

2. How Exchange Rates Create Gains and Losses

Even though stablecoins track the US dollar, they are not treated as foreign currency for tax purposes.

This creates an important distinction. Personal foreign currency gains are generally exempt for individuals (e.g. when held in bank accounts or for personal use abroad), but stablecoins fall within Capital Gains Tax rules.

As a result, movements in the GBP/USD exchange rate can create taxable gains or losses when you dispose of stablecoins.

In practice, this is where many investors are caught out. The token itself may not have increased in value, but the sterling equivalent has.

For example, if the pound weakens against the dollar while you hold USDT, the GBP value of your holdings increases. This can result in a taxable gain when you dispose of them.

Example: Holding USDT
David buys 10,000 USDT when the GBP/USD rate is 1.25 (cost £8,000).

Later, he swaps the same 10,000 USDT back into ETH when the GBP/USD rate is 1.20. His USDT are now worth £8,333.

Even though each USDT remained stable at 1 USD, David made a £333 capital gain purely because of the currency movement. This must be reported for CGT purposes.

Contrast this with a scenario where an investor holds USD in fiat and experiences the same movements in the GBP/USD exchange rate:

Example: Holding USD fiat
David holds $10,000 in a foreign currency bank account, acquired when GBP/USD was 1.25, therefore costing £8,000 at the time.

When GBP/USD later moves to 1.20, his $10,000 would be worth £8,333.

However, because this is fiat currency held in a bank account, no Capital Gains Tax applies. Individuals are not taxed on exchange rate gains or losses from personal foreign currency holdings.

This highlights a common misunderstanding. While fiat currency gains are usually exempt for individuals, holding stablecoins like USDT or USDC can trigger taxable gains from exchange rate movements alone. Investors relying on stablecoins as a “cash equivalent” can therefore be exposed to unexpected tax liabilities.

What about GBP-pegged stablecoins?

Not all stablecoins are linked to the US dollar. Some tokens, such as tGBP, are designed to track the value of the pound sterling instead.

From a tax perspective, these are still treated as cryptoassets. This means that disposing of a GBP stablecoin is still a taxable event under Capital Gains Tax rules.

However, where the token maintains a consistent 1:1 peg with GBP, there is typically no gain or loss arising on disposal, as both the acquisition and disposal values are measured in pounds sterling.

This contrasts with USD-pegged stablecoins, where exchange rate movements between GBP and USD can create taxable gains or losses even when the token itself remains stable.

3. Record Keeping

As with other cryptoassets, you need to keep accurate records of all stablecoin transactions. You should retain:

• dates of each transaction;
• amounts acquired or disposed of;
• market value in pounds sterling at the time of each transaction;
• details of any swaps or conversions.

Crypto tax software such as Koinly or Recap can help automate this process. However, outputs should always be reviewed to ensure completeness and accuracy.

4. HMRC Consultation on Stablecoins

In March 2026, HMRC opened a consultation on the taxation of stablecoins, including whether certain types of stablecoin should be treated as “exempt assets” for Capital Gains Tax purposes.

One of the options under consideration is to remove the requirement to treat disposals of qualifying stablecoins as chargeable events. In practice, this would represent a significant change to how stablecoins are taxed in the UK.

If implemented, this could mean that converting a qualifying stablecoin into fiat currency would no longer give rise to a Capital Gains Tax calculation. This would bring the treatment closer to that of holding foreign currency, where exchange rate movements are generally ignored for individuals.

This would directly address one of the key points discussed earlier in this article. At present, stablecoins are treated as cryptoassets, meaning that GBP/USD movements can create taxable gains even where the token itself remains stable in value.

Under an exempt asset approach, those foreign exchange movements may no longer be taxed, removing a common source of unexpected gains for investors.

However, it is important to note that this would not remove Capital Gains Tax entirely from transactions involving stablecoins. Disposing of other cryptoassets into stablecoins would still be treated as a taxable event, as you would still be disposing of the original chargeable asset.

At the time of writing, this is a consultation rather than a confirmed change. The scope of any exemption, including which stablecoins would qualify, has not yet been finalised.

Conclusion

Stablecoins may feel like digital cash, but HMRC does not treat them as currency. Each disposal is subject to Capital Gains Tax, and exchange rate movements can create gains or losses even where the token price remains stable.

As stablecoins become more widely used, this is an area where mistakes are common, particularly where investors assume there are no tax consequences.

If you are unsure how to calculate your gains or whether your reporting is accurate, we can help you review your position before you file.

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