Selling crypto at a loss can look like a simple way to shelter gains before 5 April. Yet if you buy the same token back within 30 days, HMRC may match your sale to that new purchase rather than your existing Section 104 pool. The loss you expected can change, shrink or arise on a different cost basis, leaving your Self Assessment calculation exposed to error.
You can claim a capital loss only when HMRC treats it as realised, usually after a disposal or through a valid negligible value claim. Selling now may reduce taxable gains, but a repurchase within 30 days can change the matching outcome. Compare the tax saving, recovery potential, available gains and your transaction evidence before acting.
Claim crypto losses now? Use four CGT tests
A claim is useful only where it can offset taxable gains, you can accept being out of the market, and no same-day or 30-day purchase changes the calculation.
A sensible CGT decision weighs four facts together: the tax saved this year, the chance and size of a price recovery, your need to keep crypto exposure, and the risk that HMRC matching rules will redirect the loss. Selling is usually sensible where gains already exist and the holding no longer fits your investment plan. Waiting is often more coherent where no gains are available, you want the exposure, or a repurchase would happen within 30 days.
Can this loss reduce tax this year?
An allowable crypto loss can offset gains from cryptoassets, shares and investment property, but not salary, pensions or other income. Unused claimed losses can usually be carried forward.
Is recovery worth more than the tax saving?
Four checks before selling crypto at a loss
1. Usable gains
Do taxable gains exist now or soon?
2. Tax value
Estimate relief at 18% or 24%.
3. Market exposure
Can you stay out for 31 days?
4. Matching records
Check all purchases by token and date.
A paper loss needs a real crypto disposal
A lower token price creates no CGT relief until a disposal or a valid negligible value claim makes the loss real.
Which actions count as a disposal?
A cryptoasset disposal is not limited to selling tokens for sterling. Exchanging Bitcoin for Ether, using tokens to buy goods or services, or giving tokens to someone other than a spouse or civil partner can also be a disposal at market value for CGT purposes. For example, if tokens acquired for £8,000 are exchanged for another cryptoasset worth £5,000, the transaction can create a £3,000 crypto capital loss even though no cash reaches your bank account.
By contrast, moving the same tokens between wallets or exchanges that you beneficially own is normally not a disposal. Record the sterling market value, fees, date, token quantity and counterparty or platform for each event.
When can a worthless token be claimed?
A negligible value claim may treat an asset still owned as disposed of and reacquired for nil proceeds where it has little or no value. Evidence may include a failed project, no viable market and no realistic prospect of sale.
Rebuying Bitcoin can defeat the loss in 30 days
Selling and rebuying the same token within 30 days can stop the expected Section 104 pool loss. HMRC matches disposals with same-day acquisitions first, then acquisitions in the following 30 days.
| Choice | Immediate CGT position | Exposure after action | Key evidence |
|---|
| Hold the token | No realised loss | Full exposure remains | Cost and holding records |
| Sell and remain out | Loss may use Section 104 pool | No exposure | Sale value, pooled cost, fees |
| Sell, rebuy after 30 days | Usually avoids 30-day matching | Out for at least 31 days | All purchases across platforms |
| Negligible value claim | Possible deemed loss if valid | Asset remains held | Proof it has negligible value |
Does same-day buying come first?
Same-day acquisitions take priority over the 30-day rule, and only the remaining disposal can use the Section 104 pool. Check recurring buys, bots and every platform before trading.
What changes after day 30?
The HMRC 30-day rule can materially change the number you report. Assume your Section 104 pool contains 1 BTC with an allowable cost of £50,000. You sell it for £35,000, apparently creating a £15,000 loss. If you buy 1 BTC for £36,000 within the following 30 days, the sale is matched with that later acquisition, so the loss is only £1,000 before fees; the £50,000 historic cost remains in the pool. At a 24% CGT rate, that changes potential Capital Gains Tax relief from £3,600 to £240.
The same-day matching rule takes priority, so recurring purchases and Bitcoin rebuying on the sale date must be checked first. A repurchase on day 31 is generally outside the 30-day matching window, but market recovery while you are out of the market remains an investment risk.
Avoid HMRC errors before Self Assessment
Report valid losses and retain evidence even where no gains are available today.
What records should support the claim?
Keep CSV files, trade confirmations, wallet transaction IDs, sterling values, fees and the token-by-token pooled-cost calculation. Reconcile every exchange and wallet, because an automated buy elsewhere can trigger matching.
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Available on Amazon
A current UK crypto tax reference book can help you organise trade records before completing Self Assessment. It is most useful as a checking tool alongside HMRC guidance, not as a substitute for tailored advice.
- Explains CGT terms such as allowable cost and Section 104 pooling in one place
- Provides a desk reference while reconciling exchange CSV files and wallet records
- Helps identify questions to raise with a UK crypto tax accountant before filing
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When does this framework not provide the main answer?
This decision framework does not apply as the main answer if you are not UK tax resident, the holding sits in a product with different tax treatment, or the movement is only between wallets you own. Seek tailored advice for DeFi, staking, derivatives, tokens received through employment, lost private keys, theft, scams or exchange insolvency. These events do not automatically create an allowable CGT loss, and the facts can be uncertain.
Timing affects administration as well as the tax result. The UK tax year ends on 5 April, so a disposal on 4 April 2026 falls in 2025/26, while one on 6 April falls in 2026/27. Where a 2025/26 return is required, the normal online Self Assessment tax return filing and payment deadline is 31 January 2027. A capital loss can generally be claimed within four years after the end of the tax year in which it arose; therefore, the usual deadline for a 2025/26 loss is 5 April 2030.
Once claimed, a capital loss carry-forward can be used against later taxable capital gains, subject to the applicable ordering rules. Keep crypto transaction records, exchange CSV exports, wallet addresses, transaction hashes, sterling valuations and fee evidence for at least the normal HMRC record-retention period.
Your questions answered
Can you claim crypto losses on taxes in the UK?
You can claim an allowable capital loss after a disposal or a valid negligible value claim. A price fall alone is not enough, and the loss should be reported to HMRC within four years after the relevant tax year ends.
Can crypto losses offset gains on shares?
An allowable loss can generally offset taxable gains on shares, investment property and other CGT assets. It cannot reduce Income Tax on wages, pensions or staking income.
What is the 30-day rule for crypto in the UK?
HMRC matches a crypto sale with purchases of the same token made in the following 30 days before the Section 104 pool. Rebuying quickly can therefore remove or reduce the immediate loss you expected.
Can I buy Bitcoin back after selling it at a loss?
You can buy Bitcoin back, but waiting at least 31 days usually avoids the 30-day matching rule. Same-day purchases still need checking, and market prices may rise while you are out.
Do I need to report a crypto loss with no gains?
You should report a valid loss even with no gains if you may want to carry it forward. For a loss in 2025/26, the usual deadline to notify HMRC is 5 April 2030.
Can I claim a loss for stolen crypto or a failed exchange?
Stolen crypto or an exchange failure does not automatically create a CGT loss. The precise facts, remaining rights against the exchange and any negligible value claim must be reviewed before filing.
Does holding crypto for longer avoid Capital Gains Tax?
No UK holding period automatically removes Capital Gains Tax from crypto. CGT depends on a disposal, the calculated gain or loss, and applicable reliefs rather than the number of months held.
Choose the tax result you can evidence
Before trading, list every purchase of the token across platforms, calculate the disposal and decide whether you can remain out for 31 days.
The essentials:- A market fall becomes an allowable CGT loss only after a disposal or a valid negligible value claim.
- Crypto losses can offset taxable gains on crypto, shares and investment property, but not Income Tax.
- Same-day and 30-day purchases can change which cost HMRC assigns to your sale.
- Report losses within the four-year window, even where no gains exist in the current tax year.
Further reading
If you want to learn more about this topic, these sources may interest you:
