The bed and breakfast rule in crypto, the 30-day trap
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Every January somebody plans the same clever move. Sell the coins that are down, bank the loss against the year’s gains, buy the coins straight back, portfolio unchanged, tax bill smaller. The bed and breakfast rule exists specifically to stop this, and with crypto’s trading speed it catches far more people than it ever did with shares.
The rule
Dispose of a cryptoasset and buy the same asset back within 30 days, and the disposal is matched against the new purchase, not against your section 104 pool. The name comes from the old share trick of selling at close and rebuying at open, one night in the bed and breakfast. It sits in section 106A of the Taxation of Chargeable Gains Act 1992, applied to crypto through HMRC’s matching rules at CRYPTO22200.
The worked example, the one that hurts
Your ETH pool holds 10 ETH at £2,000 average. ETH trades at £1,400, so you sell 5 ETH for £7,000 expecting a £3,000 loss. Six days later you buy 5 ETH back at £1,450, costing £7,250. The rebuy is inside 30 days, so the disposal matches it, not the pool.
| Amount | |
|---|---|
| Disposal proceeds | £7,000.00 |
| Matched cost, the rebuy | £7,250.00 |
| Result | £250.00 loss |
The £3,000 loss you planned does not exist. You banked £250, and your pool of 10 ETH sits at £2,000 average exactly where it was. Realising the pooled loss would have taken 31 days out of the asset, and whether that market risk is worth the tax saving is a judgement, not arithmetic.
The boundary, precisely
The statute matches acquisitions within the 30 days after the disposal, so the first clear day is day 31. Sell on 13 August and a rebuy is only outside the window from 13 September, not the 12th. The 30-day rule calculator counts the first clear day for any sale date, and runs the matching arithmetic above on your own figures, in your browser.
Count your own windows, live
The app’s harvesting view lists every open 30-day window in your actual history, per asset, counted down to its first clear day, so the question “when can I rebuy” always has a dated answer from your own records. Open the harvesting view, free under 1,000 transactions.
The order of matching, for completeness
Same-day purchases first under section 105, the following 30 days second, the pool last. Swaps count on both sides, a crypto-to-crypto trade is a disposal of one asset and an acquisition of the other, which is how active traders trip this rule weekly without noticing.
gains.tax applies the full matching order to every disposal on your own machine and labels each one with the rule that matched it and the law behind it, so a January plan can be checked before it becomes a January mistake. The complete UK guide covers all three rules with the current rates and allowances, and the app runs the real numbers on your real history, free under 1,000 transactions.