Crypto Capital Gains Tax Estimator (2025/26)

Could You Be Paying More Crypto Tax Than Necessary?

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Which CGT Rate Applies: 18% or 24%?

Crypto is classed as a chargeable asset under HMRC rules. From 2025/26 onwards, the rates for CGT on crypto are:

Band	Income Range	CGT Rate
Basic rate	Income up to £50,270	18%
Higher/additional rate	Income above £50,270	24%

Your CGT rate depends on your total income and the size of your gain. For example, if you have income of £30,270 during 2025/26, then the first £20,000 of your capital gains will be taxed at 18% and any gains in excess of £20,000 will be taxed at 24%. The interaction of capital gains tax rates with your income level presents a planning opportunity, as we have covered recently in our crypto tax planning guide.

This estimator uses your taxable income to work out how much of your unused basic rate band remains, then applies 18% to that portion of your gain and 24% to the remainder.

How the Crypto CGT Estimator Works

This tool assumes you’ve already worked out your total gain from selling, swapping, or spending crypto and you know your net gains for the tax year. If you have not, see our section below on how to calculate your crypto gains. This calculator does not take into account any crypto or other capital losses that you may have brought forward from earlier years, unless you account for those correctly in arriving at your net profit from crypto disposals.

To use the estimator, you’ll need:

• Your profit from crypto disposals (total gain minus allowable costs and losses)
• Your taxable income for the year
• The amount of CGT allowance you haven’t yet used this tax year (up to £3,000 for 2025/26)

Our estimator will:

1. Apply your CGT exemption (defaulting to £3,000)
2. Show your taxable gain
3. Work out how much of that gain falls into the unused basic rate band
4. Estimate your total CGT liability, with a breakdown of gains taxed at 18% and 24%

How to Calculate Your Crypto Gains Before Using This Estimator

Calculating your crypto gains for tax purposes in the UK comes down to one key principle: subtracting your allowable costs from your "proceeds" when you sell, swap, spend crypto or otherwise dispose of your crypto.

In some circumstances, "proceeds" can be deemed proceeds, such as when gifting crypto to a friend, child, or sibling.

In respect of allowable acquisition costs, HMRC rules require you to use share pooling (Section 104), which means grouping all your crypto purchases for particular coins together to calculate an average cost, and the matching rules, which dictate the order in which disposals are matched with acquisitions.

Step 1: Gather your transaction history

Include every buy, sell, swap, gift and fee for the tax year. HMRC expects a full record of all disposals, even small swaps between tokens.

Step 2: Apply HMRC matching rules

The UK has specific rules that dictate which crypto purchases are matched with each disposal:

• Same-day rule – sales and purchases on the same day are matched first.
• 30-day rule – if you buy crypto within 30 days of selling, those purchases are matched next.
• Section 104 pool – everything else is grouped together, and you use an average cost for those tokens. Maintain a separate pool for each token type (e.g. BTC, ETH).

Following these rules will give you your matched or pooled costs for each disposal you made in the tax year.

Step 3: Calculate your gain or loss

Take what you received (your proceeds or deemed proceeds) for each disposal and subtract your matched or pooled allowable cost. Deduct any other expenses, such as fees associated with the disposal.

Step 4: Add them up for the year

Add all gains and subtract all losses for the tax year. If your total gain exceeds the annual exemption, you may owe Capital Gains Tax.

Using Crypto Tax Software

In practice, the above is difficult to do manually unless your transaction history is relatively limited, which is why we recommend using crypto tax software. If you already use software like Koinly, the good news is these rules are applied automatically. Simply import your transactions, tag them appropriately, and Koinly produces a summary like this:

Take the Capital gains / P&L figure from your report and enter it into our estimator to get an instant UK CGT estimate:

FAQs About This Crypto CGT Estimator

How does this crypto CGT estimator work?
It takes your net crypto gains, deducts any unused annual exempt amount, then uses your taxable income to work out how much of your gain is taxed at 18% and how much is taxed at 24%.

How does this estimator use my income?
It uses your taxable income to work out how much of your basic rate band remains. Any gains within that band are taxed at 18%, with the remainder taxed at 24%.

Can I reduce my gain with other losses?
This estimator doesn’t factor in previous crypto losses automatically. But yes, if you’ve made capital losses in the same or earlier years, you can offset them against your gain before applying the exemption. You’ll need to do this manually.

Can I still use this estimator if I’ve made lots of trades?
Yes, but only if you have already applied the matching and pooling rules and arrived at your net taxable gains for the year. If you have not done that yet, see our guide to crypto share pooling.