If you used BTC to buy an ICO token, HMRC will usually see a disposal of BTC at the moment the exchange completed. The taxable amount is the GBP value of the BTC at that instant, not the later price of the new token.
If the deal is a token swap or migration, the label used by the project does not decide the tax result. HMRC looks at what changed economically: whether you gave up one asset, received another, or received a reward for taking part.
BTC used to buy an ICO token
Using BTC to buy an ICO token is normally a disposal of BTC for CGT purposes. HMRC cares about the sterling value of the BTC at the exact moment the token purchase completes, even if the ICO token cannot yet be sold.
Token swap or migration with BTC
A token swap or migration is not always a clean disposal of one asset and acquisition of another. In some restructurings, the project may present it as a continuity event, but that does not end the analysis for UK tax.
Income Tax can apply where the token is received as a reward, allocation, airdrop linked to a service, or another form of consideration for activity. It is not enough to say “I swapped BTC” if the facts show you received a benefit for doing something other than investing.
Exact GBP value at the transaction time
The sterling value at the exact transaction time is the anchor for both disposal proceeds and acquisition cost. Use the timestamp that matches the blockchain transfer or exchange execution, then apply a reasonable GBP market rate from a recognised venue.
A defensible valuation is usually built from the transaction timestamp, one or more exchange quotes, the blockchain hash, and a short note explaining why that GBP rate was chosen.
A practical example helps to show why the label on the project page is not decisive. Suppose you bought 0.2 BTC for £6,000, then used 0.1 BTC to enter an ICO at the exact transaction timestamp when 0.1 BTC was worth £3,200. HMRC would usually treat that as a Bitcoin disposal for capital gains tax, with proceeds of £3,200 against the relevant section 104 pool cost for that 0.1 BTC. If the ICO token was credited immediately, its acquisition cost would normally be £3,200 plus any allowable fee in GBP terms.
If the token later rises to £5,000 and you sell it, the later gain is calculated separately. The key point is that the taxable disposal happens at the moment the BTC leaves your wallet, not when the ICO token becomes liquid or when you finally cash out.
How HMRC treats the swap in practice
HMRC usually looks first at whether you disposed of BTC and acquired a different cryptoasset. If you did, the BTC disposal is a CGT event unless a narrow relief or reorganisation analysis applies.
The HM Revenue & Customs Cryptoassets Manual reflects this approach, and it fits the wider UK tax law treatment of exchange tokens.
Disposal of exchange tokens
Bitcoin is an exchange token for HMRC purposes. When you trade BTC for an ICO token or another coin, you usually dispose of part of your BTC pool at the exchange date and time.
Acquisition cost of the new token
The token you receive usually has a new GBP base cost at the time you acquire it. That matters because the next disposal of that token will use the receipt value as part of the gain calculation.
Income tax triggers on rewards
Income Tax is more likely where the receipt is not a simple exchange but a reward, allocation, or service-linked grant. This includes situations where tokens are issued because you staked, referred, promoted, or performed work for the project.
Reorganisation vs simple swap
A genuine reorganisation can change the analysis, but it needs facts, not assumptions. If the old token is replaced under a protocol change and holders receive a mechanically linked replacement, there may be less scope for an immediate gain than where BTC was actively exchanged for a new ICO token.
This does not work as a blanket rule if the token was received as employment income, staking reward, or a promotional allocation. In those cases, the receipt can be taxable even when no pounds were paid out.
| Scenario |
Likely UK tax treatment |
Valuation point |
Main record needed |
| BTC used to buy an ICO token |
Usually CGT on BTC disposal |
Exact swap time |
Tx hash, GBP rate, wallet proof |
| BTC swapped for a new token |
Usually CGT, sometimes mixed with income |
Exact receipt time |
Exchange statement, chain data, fee record |
| Token migration |
May be reorganisation, or income if rewarded |
Migration snapshot |
Project notice, snapshot date, wallet logs |
| Fee paid in BTC |
CGT disposal of BTC used as fee |
Time fee was deducted |
Fee invoice, tx hash, GBP value of BTC fee |
Which scenario creates CGT or income
Your tax outcome depends on what you gave up, what you received, and why you received it. In most England cases, BTC used to buy an ICO token creates CGT first, then a new cost basis in the token acquired.
BTC paid into an ICO sale
This is the clearest CGT case. You have disposed of BTC and acquired a token at a known execution time, even if the project has no live market on day one.
BTC swapped for a replacement token
A straight swap usually gives you a CGT disposal of BTC. The new token gets a sterling acquisition cost, and a later sale of that token will create its own gain or loss.
Migration with bonus or allocation
A migration with a bonus or extra allocation is the area where many returns slip. Part of the receipt may follow capital treatment, but the bonus element can be taxable as income if it was awarded for activity or entitlement.
Fee paid in BTC for the transaction
If you paid a fee in BTC, that fee is itself a disposal of BTC. The fee does not disappear just because it is small.
The capital versus income distinction is often where taxpayers go wrong. A straightforward token swap involving BTC is commonly a taxable disposal of an exchange token, but a token migration can be different if the holder receives new tokens because of a protocol change, a snapshot, or a project reissue. By contrast, if extra tokens are granted as a bonus for staking, referring users, promoting the project, or performing work, HMRC may treat that part as income rather than capital.
The same transaction can therefore be split: the BTC disposal may create capital gains tax, while the extra allocation can fall under income tax on rewards. HMRC will look at the real substance of the arrangement, not just the wording used by the project or exchange.
Calculate the gain with the right cost basis
You calculate the gain by matching BTC disposal proceeds against your pooled BTC cost, plus any allowable transaction fees. For the token you received, the receipt value becomes the acquisition cost for the next disposal.
If you hold multiple BTC buys, use the UK section 104 pool rules unless you have a same-day or 30-day match to apply.
Use the exact transaction timestamp
Use the exact time the swap or receipt happened, not the date you noticed it in your wallet. If the project ran on a decentralised exchange, the block time and the execution timestamp are the evidence that usually matters most.
If no liquid market existed, you still need a supportable value. That may be the project’s published sale price, a price from a comparable exchange, or an average of a small number of quoted venues, provided you can show the evidence.
Pooling and acquisition cost
Your BTC pool must be reduced by the correct disposal amount, and the token received gets its own starting value. If the transaction fee was paid in BTC, that fee can also reduce the pool or feed into the disposal calculation depending on the mechanics.
For Self Assessment, keep the computation in pounds sterling, not in token units alone. HMRC needs the GBP gain, the transaction date, and the supporting valuation method.
What to keep for self assessment
You should keep enough evidence to reconstruct the trade from scratch. That usually means the transaction hash, wallet addresses, exchange statements, screenshots of the sale or swap, and the GBP rate used.
HMRC expects records for at least five years after the 31 January filing deadline for the tax year, and longer is sensible for complex swaps.
The core documents HMRC will expect
Keep the on-chain hash, the sending and receiving wallet addresses, and the exchange or project statement. If you paid fees in BTC, keep the fee amount and the timestamp for that deduction too.
Capital gains from BTC disposals usually go on the Capital Gains pages of Self Assessment. Income from rewards, bonuses, or allocations usually belongs in the relevant income section, depending on the source and facts.
A practical filing checklist
Check the disposal date, the GBP value, the fee treatment, and the acquisition cost of the new token. Then test whether any part of the receipt was a reward or bonus.
For UK crypto tax reporting, strong records make the difference between a defensible calculation and an unsupported estimate. Keep the blockchain hash, the transaction timestamp, wallet addresses, exchange statements, screenshots of the ICO or swap confirmation, and a note showing how you arrived at the sterling valuation. If the token had no liquid market at the time, record the published sale price, the nearest exchange quote, or the project’s own reference price, together with the reason that method was chosen.
In Self Assessment, capital disposals normally go on the Capital Gains pages, while any income element should be reported in the relevant income section. A clear paper trail also helps if HMRC later asks why the acquisition cost and disposal proceeds differ from the headline token price on the day.
Common questions
Is an ICO token bought with BTC taxable in the UK?
Yes, usually as a BTC disposal for Capital Gains Tax. The taxable figure is the GBP value at the exact purchase time, not the later token price.
Do token swaps always create tax in england?
No, but many do. A straight swap often creates CGT, while a reward or bonus can create Income Tax instead.
What if the new token had no market price yet?
You still need a reasonable GBP valuation. Use contemporaneous evidence such as project pricing, exchange data, and screenshots taken at receipt.
Is a token migration always tax free?
No, and that assumption causes errors. A migration can be a reorganisation in some facts, but bonus tokens or reward allocations may still be taxable.
Do i report the BTC fee separately?
Usually yes, because paying a fee in BTC is itself a disposal. The BTC used for the fee needs a GBP value at the time it left your wallet.
What records should i keep for HMRC?
Keep transaction hashes, wallet addresses, exchange statements, screenshots, valuation notes, and fee details. HMRC expects enough evidence to rebuild the transaction in sterling.
Can the same event create both CGT and income tax?
Yes. That happens when part of the receipt is a capital swap and part is a reward, allocation, or other income item.
The key takeaway
An ICO or token swap involving BTC is often taxable in the UK because BTC is usually disposed of at the moment of exchange. The safest approach is to value the BTC and the received token in pounds at that exact time, then decide whether the receipt is CGT, income, or both.
Keep the blockchain proof, the GBP valuation, and the fee record together. If the swap involved no liquid market or included a bonus, treat that as a higher-risk case and document the method you used.
If you need to report it in Self Assessment, the question is not whether the wallet name changed. The question is whether you disposed of BTC, what you received, and whether HMRC would view any part of it as earnings rather than a capital exchange.
