Capital Gains Tax on Crypto 2026/27: HMRC Rules, Rates and Pooling

HMRC's Treatment of Crypto as a Capital Asset

HMRC's guidance (CRYPTO10100 and onwards) is clear: for most individuals, cryptocurrency is a capital asset, and disposals are subject to capital gains tax. A disposal includes selling crypto for fiat currency, exchanging one cryptocurrency for another, using crypto to pay for goods or services, and gifting crypto (except to a spouse or civil partner). Each disposal creates a separate CGT event.

The CGT rates for 2026/27 are 18% for gains within the basic-rate band and 24% for gains in the higher-rate band. The annual exempt amount of £3,000 applies in the same way as for shares or property. Income from crypto activities such as staking rewards, mining and airdrops may be treated as income rather than capital gain, HMRC's position is complex and depends on the facts of each case.

The Section 104 Pooling Rules

HMRC applies the same share pooling rules (Section 104 TCGA 1992) to crypto that apply to shares. Each type of cryptocurrency is treated as a single pool. When you acquire the same type of crypto on different dates at different prices, the total cost is pooled and averaged. When you dispose of some of the pool, you use the averaged cost per unit to calculate the gain.

For example, if you bought 1 Bitcoin at £20,000 and then another at £30,000, your pool contains 2 Bitcoin at a total cost of £50,000, an average of £25,000 per Bitcoin. If you then sell 1 Bitcoin for £35,000, your gain is £35,000 − £25,000 = £10,000. The remaining Bitcoin in the pool has a cost of £25,000. Each type of crypto (Bitcoin, Ethereum, etc.) is treated as a separate pool.

Same-Day and 30-Day Matching Rules

Before the pool is used, HMRC applies priority matching rules. If you buy and sell the same crypto on the same day, the buy and sell are matched against each other (same-day rule). If you sell and then buy the same crypto within 30 days, the purchase is matched against the sale (the 30-day rule, also known as the bed-and-breakfast rule). These rules exist to prevent tax avoidance through rapid recycling of crypto holdings.

The 30-day rule is particularly important for crypto investors who try to crystallise a loss by selling and immediately repurchasing the same asset. If you sell Bitcoin at a loss and buy it back within 30 days, the loss is matched against the new acquisition rather than the pool, potentially neutralising the tax planning. To crystallise a loss properly, you must wait more than 30 days before repurchasing, or switch to a different but correlated asset in the interim.

Record-Keeping Requirements

HMRC requires crypto investors to keep detailed records of every transaction: the date, the amount of crypto, the value in sterling at the date of the transaction, the exchange used and the purpose of the transaction. Without complete records, it is impossible to calculate accurate gains and losses, and HMRC can challenge any CGT return.

Many exchanges provide transaction histories that can be downloaded as CSV files. There are also dedicated crypto tax software tools that connect to exchange APIs and calculate CGT automatically using HMRC's pooling rules. Given the complexity of the rules and the high volume of transactions that active crypto traders can accumulate, using dedicated software is strongly recommended over manual calculation.