What is the section 104 pool for crypto?

A single running pool for each token, holding every unit not matched by the same day or 30 day rules at one weighted average cost. There is one pool per token across all your wallets and exchanges, because pooling follows beneficial ownership rather than where the coins are held.

Are NFTs pooled for UK capital gains tax?

No. HMRC's CRYPTO22200 states that non-fungible tokens are separately identifiable, so they are not pooled and no matching rules are applied to them. Each NFT carries its own acquisition cost. Tools that pool NFTs with fungible tokens can produce a gain or loss that does not exist.

Is moving crypto between my own wallets taxable?

No. A transfer between wallets you control is not a disposal, and your pool is unaffected. Problems arise when only one side of the transfer appears in an export, because software then reads the send as a sale and the receipt as an acquisition at nil cost, which inflates the gain.

What happens if I lose my crypto or it is stolen?

Losing a private key is not a disposal, because per CRYPTO22400 the tokens still exist on the distributed ledger. To crystallise a loss you need a negligible value claim, and if HMRC accepts it you are treated as having disposed of and immediately reacquired the tokens.

Do I pay tax when I swap one cryptocurrency for another?

Yes. Swapping token A for token B disposes of token A even though no pounds changed hands. The proceeds are the sterling value at the moment of the swap, and that same value becomes the acquisition cost of token B.

How is staking or mining income taxed in the UK?

It is taxed as income on the sterling value at the moment you receive it. Under section 37 TCGA 1992 that same value becomes the base cost of the tokens, so when you later sell them only the movement since receipt is a capital gain. Mining equipment and electricity are not allowable costs against the gain.

Crypto tax calculator

Q: How do I calculate crypto tax in the UK?

Match each disposal against your acquisitions in HMRC's fixed order. Same day first, then anything acquired in the 30 days after the disposal, then the section 104 pool, which holds every remaining unit of that token at one weighted average cost. Deduct allowable costs, add the gains up, take off the £3,000 annual exempt amount, then apply 18% to whatever fits in your remaining basic rate band and 24% above it.

Paste your history and this works the gain out the way HMRC does, applying the same day rule, the 30 day rule and the section 104 pool in the right order. It also tells you which rows are wrong and how to fix them, which is usually where the money is.

Nothing is uploaded anywhere. The whole calculation runs inside your browser, there is no account and no email.

Paste the CSV from Koinly, CoinTracker, an exchange export, or your own spreadsheet

Choose a file

Value is the sterling value of the whole transaction, not the unit price. A swap of one coin for another is a disposal of what you gave up, so use the Trade type or enter it as a sell and a buy at the same value. Moving coins between wallets you own is not a disposal, so record both sides as transfers and the calculator will leave your cost basis alone.

Paste a CSV or add transactions above, then choose Calculate.

Disposals0

Proceeds£0

Allowable costs£0

Gains£0

Losses£0

Net position£0

Income received in crypto£0

Your taxable income this year

Decides how much of the gain sits in the 18% band.

Losses brought forward

Only losses you have already notified to HMRC count.

Brought forward losses used£0

Annual exempt amount£0

Taxable gain£0

Taxed at 18%£0

Taxed at 24%£0

£0

estimated capital gains tax, 2026 to 2027

Why a crypto gain is not proceeds minus what you paid

HMRC does not let you choose which coins you sold. Every disposal is matched against your acquisitions in a fixed order set out in CRYPTO22200 and sections 105 and 106A of the Taxation of Chargeable Gains Act 1992. Same day first, then anything bought in the 30 days after the disposal, then the section 104 pool, which holds every remaining unit of that token at one weighted average cost.

The 30 day rule runs forwards, not backwards, which catches nearly everybody out. It exists so that selling and immediately buying back cannot manufacture a loss, and it applies whether or not that was your intention.

The rules this calculator applies

Pooling and matching. One section 104 pool per token, across every wallet and exchange, because the pool follows the beneficial owner rather than where the coins sit.

NFTs are not pooled. CRYPTO22200 treats them as separately identifiable, so no matching rules apply to them at all. Most calculators pool NFTs with everything else, which can invent a loss that is not there.

Crypto for crypto is a disposal. Swapping one token for another disposes of the one you gave up at its sterling value, even though no pounds moved.

Income becomes your cost. Staking, mining and airdrop receipts are taxed as income on the value at receipt, and under section 37 that same value is the base cost of the tokens, so you are not taxed twice on it.

Allowable costs. Per CRYPTO22150 and section 38, the sterling consideration, transaction fees, and professional or valuation costs are deductible. Mining equipment and electricity are not, and neither is anything already deducted against profits for Income Tax.

Gifts. To a spouse or civil partner it is no gain no loss under section 58, and they inherit your cost. To anyone else it is a disposal at market value under section 17, even though you received nothing. To a charity it is no gain no loss under section 257.

Lost or stolen coins. Losing a private key is not a disposal, because per CRYPTO22400 the tokens still exist. You need a negligible value claim before any loss can be crystallised, and the calculator says so rather than quietly writing the loss off for you.

Forks. New tokens get their own pool, with the original cost split on a just and reasonable basis under section 52(4).

The checks are the point

Most reports we are asked to correct are not wrong because the arithmetic failed. They are wrong because the data underneath was incomplete, and the software priced it anyway. A transfer between two of your own wallets, with only one side exported, gets read as a sale on one end and a nil cost purchase on the other. The pool loses its cost basis and every later disposal looks more profitable than it was.

So this tool refuses to guess. Where a row cannot be placed it says so, tells you what the consequence is, and tells you what to add. That is the same review we do by hand when someone sends us a finished report and asks whether the number is real.

What it does not do

It does not fetch market prices, so the sterling value of each row is yours to supply. It does not connect to exchange APIs, which would mean holding your API keys on a server, and a browser cannot call those endpoints directly in any case. It assumes you are investing rather than trading, a question decided by the badges of trade. It uses England, Wales and Northern Ireland thresholds. Treat the working paper as a properly reasoned computation on the data you gave it, not as a filed return.

Rates used are 2026 to 2027, a £3,000 annual exempt amount, 18% and 24%, with the basic rate band ending at £50,270 of total income.

Flagged something you cannot fix?

Missing cost basis and unpaired transfers are exactly what we rebuild. Send the working paper over and we will tell you what the pool should actually look like.

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