Crypto Exchange Transaction Analysis UK

Almost every crypto tax problem is really a data problem. The law is usually workable once you know what actually happened. The difficulty is that the record of what happened is scattered across a dozen exchanges, several wallets, three chains, a hardware device and a spreadsheet — and some of it no longer exists.

Dense red network cabling in a data centre rack, representing on-chain transaction data — Almost every crypto tax problem is really a data problem.

Why crypto transaction analysis is a specialist job

HMRC requires you to keep, for every transaction, the type of cryptoasset, the date, whether it was bought or sold, the number of units, the sterling value at the date of the transaction, the cumulative total of units held, and your bank statements and wallet addresses (CRYPTO10400). HMRC is candid about why that burden sits with you rather than with the exchange: exchanges keep records for only limited periods, and some cease to exist altogether.

There is a further problem that catches almost everyone. Because cryptoassets of the same type sit in a single section 104 pool, the pooled cost carries forward indefinitely. A disposal you make in 2026 can depend on an acquisition you made in 2016. The statutory minimum record-retention periods are therefore not an adequate guide for cryptoassets — the records need to survive for as long as any part of the pool does.

From scattered exports and on-chain records to a single defensible position.

What we reconcile

Source	What we do with it
Centralised exchange exports and APIs Binance, Coinbase, Kraken, Bitstamp, Crypto.com, KuCoin, Bybit, OKX, Gemini, Bitfinex and others	Normalise inconsistent export formats, resolve duplicated and mislabelled rows, identify internal transfers so they are not double-counted as disposals, and convert every line to sterling at the transaction date.
On-chain wallet activity Bitcoin, Ethereum and EVM chains, Solana, Cardano, Polkadot, Layer 2 networks	Trace every address you have controlled, classify transfers between your own addresses as non-disposals (beneficial ownership retained, CRYPTO22100), and identify contract interactions that are disposals even though nothing was cashed out.
DeFi protocol interactions	Decode deposits, withdrawals, LP token mints and burns, swaps, wraps and bridge transactions, and analyse each against HMRC’s beneficial-ownership test.
Failed, frozen and collapsed platforms	Reconstruct positions from partial data, bank records, correspondence and on-chain deposits where the exchange export is unavailable, and quantify the claim against the estate.
Crypto tax software output Koinly, Recap, CoinTracking, CryptoTaxCalculator, Accointing, BittyTax	Software is a starting point, not an answer. We review, correct and challenge the classifications it produces — unmatched transfers, wrong cost bases, missing pool history and misclassified income are routine.
Bank and card statements	Tie the fiat in and out to the crypto record. This is what makes the whole reconstruction defensible to HMRC.

Two accountants reconciling records together on laptops in an office — Software produces a starting position. Judgement is what changes the tax.

Where reconstructions usually go wrong

Transfers treated as disposals. Moving coins between your own wallets is not a disposal, because you retain beneficial ownership throughout. Software that cannot see both sides of the transfer will often book a phantom gain.
Missing pool history. Import three years of data into a tool and it will happily compute gains on a zero cost base. The pool has to start where your first acquisition did.
Income events not recognised as acquisitions. Staking, mining and taxable airdrop receipts create an income charge and a base cost. Missing the second half overstates the later gain.
Fees. Transaction fees are allowable on acquisitions and disposals; fiat deposit and withdrawal fees are not. A fee paid in tokens is itself a disposal.
Same-day and 30-day matching ignored. High-frequency activity means these rules bite constantly, and they change the answer materially.
Valuation without a consistent method. HMRC requires a consistent methodology applied with reasonable care; mixing price sources between years invites challenge.

Hands working through a ledger with a calculator, rebuilding a crypto transaction history — A reconciled sterling ledger, pool computations, and the methodology note that answers an enquiry before it starts.

What you receive

A single reconciled transaction ledger in sterling, with the source of every line identified
Section 104 pool computations per token, with same-day and 30-day matching applied and shown
A separate income schedule for staking, mining, lending and airdrop receipts, with the base cost carried into the pool
Completed Self Assessment capital gains figures, including the cryptoassets boxes on the SA108
A written methodology note explaining the assumptions made where data was incomplete — the document that answers an HMRC enquiry before it starts

Frequently asked questions

My exchange has shut down and I cannot get my data. Is it hopeless?

No. On-chain records are permanent, and deposits and withdrawals to and from an exchange leave a trace on both sides. Combined with bank records and any correspondence you still hold, it is usually possible to reconstruct a position to a standard HMRC will accept, provided the methodology is documented and reasonable.

I have hundreds of thousands of transactions. Is that a problem?

No — volume is a processing question, not a conceptual one. High-volume accounts are often easier to get right than small messy ones, because the data is complete. What takes the time is the handful of unusual transactions in the middle of it.

I already use Koinly or Recap. Do I still need an accountant?

Those tools are good and we work with their output routinely. What they cannot do is exercise judgement about whether a particular DeFi interaction transferred beneficial ownership, whether an airdrop was received for a service, or whether your activity amounts to a trade. That judgement is what changes the tax.

Can you work from wallet addresses alone?

Often yes, for on-chain activity. Centralised exchange activity is not visible on-chain beyond the deposit and withdrawal, so exchange records are still needed for trades that happened inside the platform.

This page is general guidance on UK tax law as at 9 August 2026 and is not advice for any particular person or situation. Tax treatment depends on your individual circumstances and may change. Where we quote HMRC’s internal manuals, note that those manuals are guidance prepared for HMRC staff, are not law, and do not bind HMRC in an individual case. Please take advice before acting. Reviewed by the TaxDigit crypto tax team · Last reviewed 9 August 2026. Updated August 2026.

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TaxDigit is a UK crypto tax accountant practice specialising in reconstruction and reconciliation. Chartered certified accountants for cryptocurrency investors, traders and businesses, UK-wide and internationally.

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