Crypto CGT Calculator

Last updated: April 2026

HMRC crypto tax estimate

This tool estimates Capital Gains Tax for small crypto transaction sets. It covers same-day matching, the 30-day rule, and Section 104 pooling. DeFi, NFTs, margin, lost keys, and large histories need specialist records.

Calculator mode

Tax yearYour income this yearOther gains this yearAnnual exempt already used

Simple disposal

Asset nameNumber of unitsPurchase datePurchase pricePurchase feesSale dateSale priceSale fees

Disposal summary

Total disposals: 1
Sale proceeds: £25,000
Cost basis: -£15,000
Fees: -£0
Total gains: £10,000
Total losses: -£0
Net gain: £10,000
Annual exempt: -£3,000
Taxable gain: £7,000

CGT owed

£1,260

At 18% basic rate: £1,260.00
At 24% higher rate: £0.00

Matching rule applied: section-104. This is based on HMRC's same-day, 30-day, then Section 104 order.

Reporting requirement

You may need to report this to HMRC via self-assessment by 31 January following the tax year end. Reporting is usually required when total proceeds exceed GBP50,000 or gains exceed the annual exempt amount.

Disposal table

Date	Asset	Qty	Proceeds	Cost	Gain	Rule
1 Jan 2026	BITCOIN	0.5	£25,000	£15,000	£10,000	section-104

Section 104 pool status

Asset	Units	Pool cost	Avg cost/unit
BITCOIN	0	£0	£0.00

For a full HMRC-compliant tax report

Large portfolios, exchange imports, DeFi, NFTs, staking rewards, and missing GBP values need specialist reconciliation.

Generate with Koinly ->

Do I pay tax on cryptocurrency in the UK?

Yes. Selling, swapping, spending, or gifting crypto can be a taxable disposal. Transfers between your own wallets are not disposals.

What is the 30-day rule?

If you sell and rebuy the same crypto within 30 days, HMRC matches the sale to the new acquisition before using the Section 104 pool.

What is the Section 104 pool?

All units of the same token are pooled. Buys add units and cost to the pool, while disposals use average pooled cost after same-day and 30-day matching.

Is swapping crypto taxable?

Yes. Swapping BTC for ETH is a disposal of BTC and an acquisition of ETH at the GBP value at the time of the swap.

What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.