CryptoTax UK · Guide
Crypto tax loss harvesting in the UK
Tax loss harvesting means deliberately realising capital losses on crypto to offset gains and reduce your overall CGT bill. It is legal and widely used — but HMRC's 30-day bed-and-breakfast rule limits how it can be done. This page explains the strategy and the constraints. Educational only — not tax advice.
Calculate my gains and losses →How loss harvesting works
If you hold crypto that has fallen below your cost basis, selling it crystallises a capital loss. That loss may be offset against capital gains in the same tax year — reducing your net taxable gain. If you have no gains this year, the loss can be carried forward. The timing of loss harvesting within a tax year (before 5 April) matters, so plan ahead rather than waiting until the deadline.
The 30-day constraint
The key limitation is HMRC's 30-day bed-and-breakfast rule: if you sell crypto and re-buy the same crypto within 30 days, the disposal is matched against the re-purchase, neutralising the intended loss. To harvest a loss, you either need to wait 31+ days before re-buying, or substitute with a different (but correlated) asset to maintain market exposure.
Practical strategies within the rules
Common approaches: (1) Sell a position and wait 31 days before re-buying, accepting the period of non-ownership. (2) Sell one asset (e.g. BTC) and immediately buy a correlated but distinct asset (e.g. ETH) to stay in the market. (3) Use a spouse's £3,000 CGT allowance by transferring before selling. Always consider the investment implications alongside the tax ones.
Using the annual exempt amount
The £3,000 annual exempt amount cannot be carried forward — if you don't use it by 5 April, it is lost. If your gains are already under £3,000, there is no tax benefit to harvesting further losses in that year. Consider harvesting losses in years where gains are above the allowance.
Frequently asked questions
Is tax loss harvesting legal in the UK?
Yes — realising capital losses and using them to offset gains is a legitimate and legal tax planning strategy. The 30-day rule is HMRC's anti-avoidance measure to prevent immediate round-trips, not a prohibition on the strategy itself.
Can I harvest losses and reinvest in a similar crypto immediately?
You can reinvest in a different crypto immediately without triggering the 30-day rule — the rule only applies if you re-buy the same asset. Selling BTC at a loss and immediately buying ETH is not restricted.
When is the best time in the tax year to harvest losses?
Any time before 5 April, ideally with enough time to confirm your overall gains position. Many UK crypto investors review their position in February or March to decide whether harvesting makes sense.
What happens to unclaimed losses?
You must claim capital losses on your Self Assessment return within 4 years of the end of the tax year in which they arose. After that, they cannot be carried forward. Don't let valuable losses expire unclaimed.
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Calculate my gains and losses →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.