CryptoTax UK · Guide
The bed and breakfast rule for crypto in the UK
The 30-day 'bed and breakfast' rule is one of HMRC's anti-avoidance provisions for crypto. It stops investors from selling a crypto to crystallise a loss (or gain at a favourable rate) and then buying back the same asset within 30 days. This page explains how it works and why it matters. Educational only — not tax advice.
Check my matching rules →What the rule does
Under HMRC's matching rules, a disposal is matched — in priority order — against acquisitions of the same crypto on the same day (same-day rule), and then against acquisitions of the same crypto in the following 30 days (the 30-day or bed-and-breakfast rule). Only after both rules have been applied does the disposal match against the Section 104 pool. This means a re-purchase within 30 days effectively overrides the pool cost basis.
How it affects loss harvesting
If you sell ETH at a loss intending to crystallise it, then re-buy ETH within 30 days, the disposal is matched against the re-purchase price — not the pool average. This may significantly reduce or eliminate the loss you intended to claim. To avoid this, you typically need to wait at least 31 days before re-buying — or never re-buy the same asset (replacing it with a correlated but distinct one).
Worked example
You hold 1 ETH with a pool cost of £2,000. ETH falls to £1,500, so you sell to crystallise a £500 loss. Three days later ETH is still at £1,500 and you re-buy. HMRC matches the disposal against the re-purchase at £1,500 — both proceeds and cost are £1,500, giving a £0 gain or loss. Your intended £500 loss disappears. The original £2,000 pool cost is maintained.
The same-day rule
The same-day rule applies before the 30-day rule: if you sell and buy the same crypto on the same day, the disposal is matched against that day's acquisitions first — regardless of the Section 104 pool. This can catch automated trading strategies and same-day rebalancing.
Does it apply to all crypto?
Yes — the matching rules apply to all cryptoassets treated as fungible by HMRC. Each crypto (BTC, ETH, SOL etc.) has its own pool and its own matching queue. Selling BTC and buying ETH is not affected — the rule only applies when you sell and re-buy the same asset.
Frequently asked questions
Does the 30-day rule apply to gains as well as losses?
Yes. If you sell to realise a gain and re-buy the same crypto within 30 days, the disposal may be matched against the re-purchase price, potentially changing the gain. Most loss-harvesting discussions focus on losses, but the rule is symmetric.
What if I buy crypto on day 0 and sell on day 15?
The 30-day rule looks at acquisitions after the disposal. The same-day rule looks at acquisitions on the same day as the disposal. If you bought first and sold later within 30 days, the disposal would typically be matched against the Section 104 pool (those earlier buys already went into the pool before the disposal).
Does it apply to crypto held in different wallets or exchanges?
Yes — the matching rules apply across all your holdings of the same crypto regardless of where they are held. A sale on Coinbase matched against a re-purchase on Binance of the same token still triggers the 30-day rule.
How does the CryptoTaxUK calculator handle this?
The calculator automatically applies the same-day rule, then the 30-day rule, then the Section 104 pool — in the correct HMRC order — across all your transactions. The Results page shows how each disposal was matched.
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Educational guidance only. CryptoTax UK is not a regulated tax adviser and the information above does not constitute tax, legal or financial advice. Always confirm your specific position with HMRC or a qualified accountant before filing.