Crypto Tax Calculator UK 2025

HMRC treats cryptocurrency as a capital asset. When you sell, swap, or spend crypto, you may owe Capital Gains Tax on any profit. The CGT rates are 10% for basic rate taxpayers and 20% for higher rate taxpayers. Mining and staking rewards are treated as income and taxed at your income tax rate.

The Section 104 pool is the method HMRC requires for calculating cost basis. All tokens of the same type are pooled together, and the cost basis is the average cost per token. When you sell, the cost basis is calculated from this average. This prevents you from cherry-picking specific tokens to reduce tax.

The same-day rule overrides the Section 104 pool. If you buy and sell the same crypto on the same day, the cost basis is matched to the same-day purchase first. This prevents a "wash sale" where you sell and immediately rebuy at a similar price to crystallise a loss.

The bed and breakfast rule (30-day rule) prevents you from selling crypto to crystallise a loss and then rebuying within 30 days. If you rebuy the same crypto within 30 days of selling, the cost basis of the sale is matched to the repurchase price, not the Section 104 pool average.

Yes. Swapping one cryptocurrency for another (e.g., BTC to ETH) is a taxable disposal. You are deemed to have sold the first crypto at its market value and purchased the second. Capital Gains Tax applies to any gain on the disposal of the first cryptocurrency.

Yes. The annual CGT exempt amount is £3,000 for 2025/26. This covers all capital gains, not just crypto. So if you have gains from shares and crypto, the £3,000 exemption is shared across all disposals. Any gain above this is taxed at 10% or 20%.

Mining and staking rewards are treated as income by HMRC. The market value at the time you receive the tokens is taxable as miscellaneous income. When you later sell those tokens, you also owe CGT on any gain above the cost basis (the value at the time of receipt).

Yes, if your total gains exceed the annual exempt amount or your total proceeds exceed 4x the exempt amount (£12,000), you must report on your Self Assessment tax return. Even if you made a loss, you should report it to carry it forward against future gains.

Yes. Crypto losses can be offset against gains in the same tax year. Unused losses can be carried forward indefinitely. You must report losses to HMRC within 4 years. Strategic loss harvesting (selling losing positions) before the tax year end can reduce your CGT bill.

HMRC has data-sharing agreements with major UK crypto exchanges. They receive transaction data from Coinbase, Binance, Kraken, and others. HMRC has sent "nudge letters" to crypto holders encouraging voluntary disclosure. Non-disclosure can result in penalties of up to 200% of the tax owed.