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UK crypto tax for exchanges and DeFi · 2025/26

A UK crypto tax report you can actually check.

Bring your exchange files and read-only wallets together. ChainTax applies UK matching rules, shows how each gain or loss was calculated, and keeps anything that could change your tax visible for review.

200 transactions free · No card required · Reports from £49

chaintax.co.uk/reportIllustrative

Tax year 2025/26

Tax report

2 checks need your input

Report checks

Review before relying on the estimate

Recorded gains

£18,420

Taxable gain

£15,420

Current estimate

£2,775.60

How the figures connect: recorded gains minus losses and the £3,000 allowance gives the taxable gain. The current estimate applies an assumed tax profile and adds estimated tax on crypto income. The two open checks could change all three figures.

2 of 4 report checks need attention
Every material gap stays visible
See the calculation

Every sale,
explained.

A total on its own is hard to trust. Open any sale to see how much came in, what the crypto originally cost, which price was used, and how ChainTax reached the gain or loss.

  • How the original purchase was matched to the sale
  • The purchase cost used in the calculation
  • Where the pound value came from
  • Anything ChainTax is unsure about
What happens when something is missing?
  1. 1Flag it. If the original purchase cannot be found, ChainTax marks the figure as incomplete instead of assuming it is correct.
  2. 2Add the missing detail. Import the exchange file, add the original purchase, or enter a reliable market value.
  3. 3Recalculate. ChainTax reruns the report and clears the warning only when the issue is fixed.

Open every calculation yourself or send your accountant a secure, read-only link. They can see the report, but never your dashboard. See how sharing works.

chaintax.co.uk/transactions
SaleCheck complete3 Jul 2024
Sold
1.5000 ETH
Gain
+£1,847.50
How this sale was matched
Average purchase cost (HMRC Section 104)

There were no matching purchases on the same day or in the following 30 days, so HMRC's average-cost rule applies.

Average-cost record
Crypto held
Purchase cost
Before
8.2400 ETH
£18,492.00
This sale
−1.5000 ETH
−£3,366.07
After
6.7400 ETH
£15,125.93
Sale value £5,213.57·Cost £3,366.07
Price: Kraken close

Why ChainTax

Your tax figure is only as reliable as the history behind it.

ChainTax is designed for the hard part: combining scattered exchange and wallet history without hiding the uncertainty that can change the answer.

01

One history across exchanges and wallets

Bring Coinbase, Binance and Kraken; Crypto.com App (beta) files together with read-only Ethereum, Arbitrum, Optimism, Base, and Polygon wallet history.

The same asset feeds one account-wide UK tax calculation.

02

Every material disposal explained

Open a gain or loss to see the proceeds, matched purchase cost, allowable fees, price evidence, and pool movement.

A total is useful. The working is what lets you check it.

03

Anything material stays visible

Missing history, uncertain classifications, unavailable prices, and stale matching remain named review items.

A report cannot quietly look ready while evidence that could change the tax is missing.

How it works

From scattered history to working you can review.

ChainTax builds the calculation, then gives you a short, material review list. Nothing important is hidden to make the report look finished.

  1. 1

    Add your history

    Import Coinbase, Binance and Kraken; Crypto.com App (beta) CSVs and add your public wallet addresses. We never ask for private keys or permission to move funds.

  2. 2

    Let ChainTax build the working

    Supported activity is classified, priced, and matched using the UK same-day, 30-day, then Section 104 order.

  3. 3

    Review what could change the answer

    Resolve missing history, unclear activity, or prices, then inspect the report or share the same working with your accountant.

Pricing

Pay once for the tax year you need.

Light and Active use the same calculations, review checks, Show Working, and downloads. Choose by transaction count.

Free

£0

200 transactions

Import your history, inspect the classifications, and see the checks that still need your attention.

Check history free

Light

£49

2,500 transactions / tax year

Reviewable working and report downloads for a lower-volume tax year.

See Light
For active DeFi

Active

£99

10,000 transactions / tax year

The same calculations and outputs for an active DeFi tax year with more transactions.

See Active
Above 10,000 transaction records account-wide? We can handle the import for you.

What it covers

Built for complicated crypto. Honest about the boundary.

ChainTax brings supported exchange and wallet history into one UK tax report. If it finds unfamiliar activity or missing information, it asks you to review it instead of making up an answer.

  • Read-only wallet sync for Ethereum, Arbitrum, Optimism, Base, and Polygon
  • CSV imports for Coinbase, Binance and Kraken; Crypto.com App (beta) and compatible Koinly files
  • Support for many swaps, liquidity pools, staking, lending, bridges, transfers, and NFTs
  • UK capital gains, income, and fee summaries for your tax return
See exactly what ChainTax supports

Before you download

ChainTax tells you when the report still needs work.

The report is not marked ready while important history, prices, or transaction details are still missing. You always know what is holding it back and what to do next.

Purchase history is missing

Needs attention

A transaction is still unclear

Needs attention

A price could not be found

Needs attention

Everything important is checked

Ready to review

Common questions

The things people ask before they sign up.

Is it safe to connect my wallet?
Yes. You only add your public wallet address. ChainTax never asks for a seed phrase, private key, signature, or permission to move funds. It uses the same public transaction history you can see on a block explorer.
How does ChainTax work out what each transaction was?
ChainTax follows the UK matching order automatically. It first looks for purchases on the same day, then purchases in the following 30 days, then uses the average cost of the remaining holding. It recognises 34 types of supported DeFi and crypto activity. Anything unclear is put on your review list instead of being presented as solved.
What if ChainTax gets a transaction wrong?
You can correct it. Change the transaction type, amount received, purchase cost, or token. Your correction is kept when you sync again, so you only need to fix it once. ChainTax then recalculates the report.
Can my accountant verify the calculations?
Yes. Create a secure read-only link from your report. Your accountant can see every sale, the price used, the original purchase cost, and how the gain or loss was calculated. They do not need a login and cannot access your dashboard. When the checks pass, the report includes the UK tax return figures for them to review.
Which exchanges and chains do you support?
CSV import: Coinbase, Binance and Kraken; Crypto.com App (beta); plus Koinly universal CSV (compatible format). The Crypto.com App importer is in beta. It is parser-tested but has not yet been validated end to end against a current real export, so review the imported rows before relying on them.
On-chain: Ethereum, Arbitrum, Optimism, Base, and Polygon. Solana, Avalanche, BSC and others are not yet covered. For those, manual entry or a Koinly CSV is the workaround for now.
What about NFTs, staking rewards, or trades I made before signing up?
ChainTax recognises supported NFT trades and staking rewards automatically. For an unsupported marketplace or activity it cannot rebuild from public history, you can add the original purchase, sale, income, or historical price yourself. Your entry is saved for future recalculations.
Why is ChainTax cheaper than other crypto tax tools?
ChainTax report access is priced for one selected UK filing year. Your highest purchased tier sets account-wide capacity: £49 Light supports up to 2,500 transaction records and £99 Active supports up to 10,000. There is no subscription or automatic renewal, and calculation quality does not change by tier.
I have over 10,000 transaction records account-wide. Now what?
Use the Concierge service. We handle the import, work through anything that needs your input, and give you the same clear report. It is quote-first and typically costs £249–£449 depending on the size and complexity of your history. Email hello@chaintax.co.uk. For a first contact, do not send private keys, seed phrases, passwords, API secrets, authentication codes, full transaction histories, complete tax reports, unnecessary identity documents, unnecessary wallet addresses, transaction hashes, or source files. Send only the tax year or years, an approximate transaction-record band, broad source categories, broad activity types, and any deadline. We will agree the next appropriate step if more information is genuinely necessary.

Still have questions? hello@chaintax.co.uk. We read every email.

Build a UK crypto tax report you can review.

Add exchange files or read-only wallets. ChainTax brings the history together, applies UK matching rules, and keeps anything that could change your tax visible.

200 transaction records free account-wide · No card required · One payment per report tax year