How do the share pooling rules work for crypto Capital Gains Tax in the UK?

Full answer

For Capital Gains Tax, HMRC treats cryptoassets much like shares, so you cannot individually identify which specific coins you disposed of. Instead you match disposals to acquisitions using a strict ordering of rules. The matching order is: first, any tokens of the same type acquired on the same day as the disposal; second, tokens acquired in the 30 days after the disposal (the bed-and-breakfasting rule, which stops people selling and immediately rebuying to crystallise a loss); and third, the Section 104 pool. The pool holds all your remaining units of that token together with their total allowable cost, giving an average cost per unit. Each token type has its own separate pool. When you dispose - by selling for fiat, swapping one crypto for another, or spending it - you compute the gain as proceeds (market value in GBP) minus the pooled average cost for the units sold, less allowable costs such as transaction fees. The pool's total cost and unit count are then reduced proportionally. Worked example: you buy 2 BTC for GBP 20,000 and later 1 BTC for GBP 40,000. Your pool is 3 BTC costing GBP 60,000, an average of GBP 20,000 each. You sell 1 BTC for GBP 35,000. The gain is GBP 35,000 minus GBP 20,000 = GBP 15,000, and the pool drops to 2 BTC costing GBP 40,000. For 2026/27 the CGT Annual Exempt Amount is GBP 3,000. Gains above that are taxed at 18% to the extent they fall within your remaining basic-rate band and 24% above it. You must report and pay through Self Assessment if your disposals exceed the reporting limits. A capital gains tax calculator can estimate the tax once you know your pooled gain.

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