Crypto-to-crypto swaps: a taxable disposal in the UK

Almost everyone assumes the same thing, and it feels completely reasonable: no pounds left the exchange, no cash hit my bank, so there's nothing to tax. It's the most natural assumption in the world, and it's wrong. Under UK rules, swapping one cryptoasset for another is a disposal, and a disposal is exactly the moment Capital Gains Tax can bite. So before you convince yourself you're in the clear because you never “cashed out”, it's worth two minutes to understand what HMRC actually says, because it changes the picture completely.

The rule, stated plainly

HMRC's Cryptoassets Manual is unambiguous. A disposal happens when you put one token into a transaction and receive a different token back. In HMRC's own words, “exchanging tokens for a different type of token” is listed as a disposal, right alongside selling for money and spending crypto on goods. It does not matter that no pound sterling was ever involved. The moment you swap coin A for coin B, you have disposed of coin A, and any gain built up in coin A since you bought it becomes taxable there and then.

This catches people out because a swap doesn't feel like a sale. Nothing was withdrawn, nothing hit your bank, and you may still be fully invested. But HMRC treats crypto as property, not currency, so trading one property for another is a disposal of the first one, just as swapping one house for another would be. The tax follows the disposal, not the cash.

How the gain is worked out

The maths is the same as any other disposal, with one twist: because no cash changed hands, HMRC uses market valueto price the trade. This comes from the general capital gains rule (TCGA 1992 section 17) that where you don't receive money for an asset, you value the disposal at the market value of what you got instead. Here is the sequence.

• Disposal proceeds. The pound-sterling market value of the coin you received, measured at the moment of the swap. If you swap 1 BTC for some ETH when 1 BTC is worth £45,000, your disposal proceeds are £45,000, even though ETH, not pounds, landed in your account.
• Allowable cost. The pooled cost of the coin you gave up, worked out under Section 104 pooling (the weighted-average cost of all your units of that coin), after applying the same-day and 30-day matching rules first.
• Gain or loss.Disposal proceeds minus allowable cost, both in pounds. That is what's taxable (after your annual allowance).
• New base cost. The coin you receivednow enters its own pool at the same pound-sterling value you used as proceeds. So the ETH above acquires a base cost of £45,000, which is the figure you'll deduct when you eventually dispose of that ETH.

A crucial point that saves headaches: every coin has its own separate pool. Your BTC, your ETH and your USDT are never lumped together; each is tracked independently, and a swap is simultaneously a disposal out of one pool and an acquisition into another. The same-day rule, the 30-day bed-and-breakfast rule and the pool all apply to both sides of the swap.

What about the swap fee?

Trading fees on a swap are allowable, but they don't all come off one side. HMRC's guidance (based on the allowable-expenditure rules in section 38 TCGA 1992) is that a fee on an exchange of tokens is split between the two sidesof the transaction, typically 50/50 or on another just-and-reasonable basis. Part reduces the proceeds of the coin you sold, and part increases the base cost of the coin you bought. It's a small effect on any single trade, but across hundreds of swaps it adds up, and doing it correctly is exactly the kind of tedious bookkeeping software is good at.

The same rule, in every form you'll meet it

Swaps come dressed up in different clothes: a slick “Convert” button, a DeFi app, a stablecoin move that feels like parking cash. The tax treatment underneath is the same disposal rule every time. Here's how it lands in the situations people actually ask about.

On a centralised exchange (Coinbase, Binance, Kraken)

Whether you use the full trading screen or the one-tap Convert or Instant Buyfeature, a crypto-to-crypto trade on a CEX is a disposal. There is no preferential treatment for the convenient “Convert” button; it's treated exactly like a manual swap. The coin you give up is disposed of at its GBP market value at that moment, the coin you receive enters its pool at that same value, and pooling and matching rules apply to both.

On a DEX (Uniswap, 1inch and similar)

Swapping USDC for DAI on Uniswap, or any token for any other on a decentralised exchange, is treated identicallyto a swap on a centralised exchange. A swap is a swap; HMRC doesn't care whether it happened on Coinbase or on-chain through a smart contract. The disposal crystallises when the swap confirms on-chain, valued in pounds at that moment. Slippage, price impact and the DEX fee are simply part of what you actually gave and received, so they're already baked into the real GBP values you record. Both tokens carry on in their own separate pools.

Swapping into a stablecoin (BTC to USDT, ETH to USDC)

This is the big one, so let's be blunt: moving into a stablecoin is not cashing out, and it does notescape Capital Gains Tax. HMRC treats USDT and USDC as cryptoassets (exchange tokens), not as pounds and not as cash. HMRC's CRYPTO22100 does not grant stablecoins a special exemption from the disposal rule; they are treated as exchange tokens like any other cryptocurrency. So swapping BTC for USDT is a disposal of the BTC at its GBP market value, and the USDT is acquired at its GBP value at that moment (usually very close to £1 each, but you still have to value it in pounds). If your BTC had risen since you bought it, you have a taxable gain the instant you move into USDT, even though it feels like you just pressed pause. The USDT then sits in its own pool for next time.

Stablecoin to stablecoin (USDC to USDT)

Technically, still a disposal. Swapping USDC for USDT is a disposal of the USDC and an acquisition of the USDT, each valued in pounds. The good news is that on a genuine 1:1 peg the gain or loss is usually a rounding error, often effectively nil, because both sit at roughly £1. Even if the gain rounds to £0, record it as a disposal: from 2026, CARF reporting covers all disposals regardless of gain amount, so a trivial swap still belongs in your records. And “tiny gain” is not the same as “doesn't count”: the trade still feeds your pool, it counts towards the £50,000 proceeds reporting threshold, and from 2026 it's the kind of activity exchanges report to HMRC under CARF. In March 2026 HMRC ran a call for evidence (now closed) on whether to simplify this, including possibly treating certain sterling-denominated stablecoins as exempt assets, but no such change is law for 2025/26. For now, treat every stablecoin swap as a disposal.

Using crypto to buy an NFT (ETH for an NFT)

Buying an NFT with ETH is a disposal of that ETH at its GBP market value at the time of purchase, so any gain on the ETH is taxable. The NFT is then acquired at that same GBP value as its cost. One key difference: NFTs are non-fungible, so each one is a separate asset and is not pooled, unlike your fungible coins. When you later sell the NFT, its gain is the sale proceeds minus that original GBP cost. Gas and marketplace fees are allowable and can be apportioned across the ETH disposal and the NFT acquisition. There's more in our NFT tax guide.

What is not a swap (and not taxed)

For balance, one thing that people wrongly panic about: moving the same coin between your own wallets or exchanges is not a disposal. Sending BTC from Coinbase to your hardware wallet changes nothing about ownership, so there's no tax and no gain to calculate. A transfer only becomes a disposal when the coin actually changes into a different asset. So “BTC from Coinbase to cold storage, then later swapped for ETH” is two separate events: an untaxed transfer, then a taxable swap. Don't double-count the transfer, and don't miss the swap.

Where it genuinely gets murky (out of scope here)

The rules above are settled. A few adjacent cases are not, and it would be dishonest to pretend otherwise. These are genuinely fact-dependent, HMRC's guidance is still developing, and we won't resolve them in a general guide.

• Wrapping (BTC to WBTC, ETH to stETH or wstETH). Current practice generally treats the wrapped token as a separate asset, so wrapping is treated as a disposal, but this is a grey area pending clearer law. Record it carefully and get advice if the amounts are material.
• Bridging between chains (Ethereum mainnet to Arbitrum, Optimism, Polygon).HMRC's own guidance says the answer “depends on the facts”. Some canonical Layer-2 bridges may not be disposals; third-party and wrapped-token bridges more likely are. This is unsettled, and HMRC's guidance is still developing.
• DeFi liquidity pools and LP tokens.Depositing two tokens for an LP token, and later redeeming it, likely involves disposals on each leg, but whether it's treated as one swap, two simultaneous disposals, or something else is not settled. Treat as fact-dependent and take advice if it's material.

Because these are unresolved, we flag them rather than guess. If your activity is heavily in wrapping, bridging or DeFi, that's the point to speak to a qualified UK crypto tax adviser rather than rely on a rule of thumb.

“I swapped hundreds of times, am I in trouble?”

This is the fear behind most searches, so let's answer it honestly. A year of active swapping does not automatically mean a big tax bill. Every swap is a disposal, yes, but each one produces a gain or a loss, and the two net off. If your later swaps crystallised losses, those reduce the gains from earlier ones. Only your net gain above the £3,000 allowance is taxed, and losses can be carried forward if they exceed your gains. Plenty of busy traders end a year owing far less than they feared, and some owe nothing at all.

What you can't do is ignore it. Even with no tax to pay, you may still need to report if your total proceeds across all disposals top £50,000, and from 1 January 2026, exchanges report your activity to HMRC under the Cryptoasset Reporting Framework (CARF). So the safe move isn't to hope it's invisible; it's to work out the real number.

How our calculator handles this

This is exactly the tedious job software is built for, so a quick, honest note. When you upload your exchange CSV, CryptoCGT treats each swap as what HMRC says it is: a disposal of the coin you gave up, priced at its GBP value at the time, matched under the same-day, 30-day and Section 104 rules, with the coin you received pooled at that same value as its new base cost. It gives you the SA108 figuresand a dated, locked copy of the workings so you can show how each number was reached. It doesn't make the grey areas above go away, and you should always check the figures against your own records, but the pooling arithmetic across a year of swaps is precisely where it earns its keep.

New to all this? Start with how UK crypto tax works, then read Section 104 pooling for the cost-basis maths and how to report on Self Assessment when it's time to file. This is general information, not personal tax advice. If your history is large, or full of wrapping, bridging or DeFi, get it checked by a qualified adviser.

Sources

• HMRC CRYPTO22100: what counts as a disposal, including “exchanging tokens for a different type of token”
• GOV.UK: Check if you need to pay tax when you sell cryptoassets, confirming that exchanging one token for another is a disposal and gains are worked out in pound sterling
• HMRC CRYPTO22150: allowable costs under s.38 TCGA 1992, including apportioning transaction fees
• HMRC CRYPTO22200: pooling of cryptoassets, with a separate Section 104 pool per token type
• HMRC CRYPTO22110: transfers between distributed ledgers, where the answer depends on the facts
• TCGA 1992, s.17: market value rule where consideration is not money or money's worth
• TCGA 1992, s.104: pooling of assets of the same class into a single holding with pooled cost
• HMRC CG14550: market value rule for capital gains, reinforcing the s.17 principle
• HMRC call for evidence (March 2026, closed): Taxation of stablecoins, exploring whether to treat certain sterling stablecoins as exempt assets (not yet law)
• HMRC: Cryptoassets Manual