Crypto CGT Loss Crystallisation Calculator 2026

Loss crystallisation means selling a crypto asset that has fallen below your cost price before the tax year end (5 April) to realise the loss. This loss can offset gains made elsewhere, reducing your CGT bill.

Since 30 October 2024: 18% for basic rate taxpayers and 24% for higher/additional rate taxpayers. These are the same rates as other capital assets. The annual exempt amount is £3,000 for 2025/26.

If you sell cryptocurrency and repurchase the same token within 30 days, HMRC matches the disposal against the repurchase at the new cost price. This means the loss is effectively blocked — the Section 104 pool is adjusted instead.

Option 1: Wait 31+ days before repurchasing the same cryptocurrency. Option 2: Immediately swap into a different cryptocurrency (e.g., sell Bitcoin and buy Ethereum) — this is allowed as they are different assets.

Generally no. Capital losses can only offset capital gains, not income tax. Exception: if HMRC makes a negligible value claim for a specific token, you may be able to treat it as an income loss in limited circumstances.

Yes — capital losses that exceed your total capital gains in a tax year (after the annual exempt amount) can be carried forward indefinitely. They must first reduce gains in later years before the annual exempt amount applies.

You use the market price at the time of disposal in GBP. For coins traded 24/7 without a closing price, HMRC accepts the price at midnight UTC on the day of disposal. Exchange records and blockchain explorers provide auditable evidence.

HMRC requires: date of acquisition and disposal, amount of each crypto acquired/disposed, cost in GBP, disposal proceeds in GBP, pool balance after each transaction. Exchange API exports and blockchain records should be kept permanently.