Crypto losses can reduce UK Capital Gains Tax only where HMRC accepts a deductible capital loss reported correctly.
A disposal or valid claim is needed for tax relief
A loss can normally reduce Capital Gains Tax only after a disposal, meaning an event where you give up or exchange the asset, or after a valid negligible value claim.
Events that count as a crypto disposal
A disposal of cryptoassets can happen without money reaching your bank account. Selling Bitcoin for pounds is a disposal, but so is swapping Ether for another token, buying a laptop with crypto, or gifting coins to someone other than a spouse or civil partner.
- Sale for GBP: compare sale proceeds with the matched acquisition cost.
- Crypto-to-crypto swap: use the pound value of the token received at the transaction time.
- Payment with crypto: treat the purchase as a disposal at the pound value of what you bought.
- Token held after a price fall: usually no realised loss and no immediate relief.
A negligible value claim asks HMRC to treat an asset you still own as sold and immediately reacquired for nil value. It may help where a token or NFT has become genuinely worthless, not merely hard to sell or sharply down in price.
An allowable capital loss is first set against capital gains in the same tax year. Any unused amount can generally be carried forward to later years, but it cannot normally be set against salary, pension income or bank interest for a private investor.
For the 2025/26 tax year, the individual annual exempt amount is £3,000. Losses are used against gains before that allowance is applied, which can preserve more of the allowance for other gains. Report or claim the loss within the applicable deadline, commonly four years after the end of the tax year in which it arose.
Loss events have different HMRC routes and evidence
HMRC treatment depends on whether your crypto was disposed of, became worthless, or remains yours but inaccessible. A hack, rug pull, exchange insolvency and locked account may all feel like the same financial loss, but they can lead to different reporting routes under the HMRC Cryptoassets Manual.
| Loss event | Likely tax route | Evidence to retain |
|---|
| Sale or swap below cost | Capital loss on disposal | Exchange CSV, trade time, GBP values |
| Liquidation of collateral | Possible disposal, facts matter | Protocol history, loan and liquidation records |
| Hack or theft | Not automatically allowable | Wallet hashes, fraud report, ownership proof |
| Rug pull or worthless token | Possible negligible value claim | Market evidence, project records, wallet history |
| Exchange insolvency | Often wait for recovery position | Administrator emails, claim notices, balance history |
| Locked wallet or frozen funds | Usually no immediate loss | Access records, support correspondence |
Theft and hacks need proof of ownership
Lost or stolen cryptoassets do not automatically produce an allowable loss. If a scammer transfers coins from your wallet, you may still need to show whether a disposal occurred for CGT purposes, rather than assuming that theft itself creates tax relief.
Keep the public wallet address, transaction hash, screenshots made at the time, police or Action Fraud report where relevant, and records showing you controlled the wallet. A seed phrase should never be sent to HMRC or an adviser.
Failed exchanges can retain some value
An exchange balance may remain an asset even when withdrawals are blocked. If an administrator expects to return between 10% and 40% of customer funds, a claim for a 100% loss may be too early or too high.
Choose the loss route before filing
1. Did you dispose?
Sale, swap, spend or liquidation may create a CGT calculation.
2. Still own it?
Check whether a negligible value claim is genuinely supported.
3. Cannot access it?
Preserve proof and assess recovery value before claiming.
Record the event date, pound value, matching calculation and supporting documents before using the loss on Self Assessment.
Calculate pooling rules before offsetting gains
A crypto capital loss must use the same-day rule, the 30-day rule and then the Section 104 pool. The pool is a running average cost for units of the same cryptoasset, rather like mixing identical bags of rice in one cupboard and calculating the average price per bag.
A bitcoin loss with the 30-day rule
Assume Priya’s Section 104 pool contains 1 BTC costing £30,000. On 1 June, she sells 0.5 BTC for £12,000. On 15 June, she buys 0.5 BTC for £14,000.
Because the repurchase falls within 30 days, the 1 June sale matches the 15 June purchase, not her older pooled Bitcoin. Her allowable loss is £2,000 (£12,000 proceeds less £14,000 cost). The original 1 BTC pool remains unchanged at £30,000.
If Priya had not repurchased within 30 days, the sale would match the pool. Half of the pooled cost would be £15,000, creating a £3,000 loss instead. This is why an average purchase price alone can produce the wrong answer.
Report the loss and carry it forward
A Self Assessment taxpayer can enter capital gains and losses on the Capital Gains pages of the tax return. Where you do not need to file a return, you may make a standalone claim to HMRC. HMRC’s Self Assessment guidance explains the filing route, while records should normally be retained for at least five years after the 31 January filing deadline.
Suppose Priya also made a £7,000 gain on Ether in 2025/26. Her £2,000 Bitcoin loss reduces that gain to £5,000, then the £3,000 annual exempt amount leaves £2,000 taxable. If she had a £9,000 loss and only £7,000 of gains, £2,000 could usually carry forward after the current-year gains are covered.
For crypto loss reporting, an individual completing Self Assessment normally submits the main SA100 return with the Capital Gains supplementary pages, usually SA108, where the aggregate gains and allowable losses are reported. For 2025/26, an online return is normally due by 31 January 2027. A taxpayer who has no reason to file Self Assessment can make a standalone capital-loss claim to HMRC, but should state the asset, disposal or claim date, calculation and amount claimed.
The usual time limit to claim an allowable loss is four years after the end of the tax year: a 2025/26 loss would ordinarily need to be claimed by 5 April 2030. That claim deadline is different from the shorter deadline for amending a submitted tax return.
The same-day rule takes priority over both the 30-day rule and the Section 104 pool. For example, assume Daniel already has 1 ETH in his pool with a pooled cost of £2,000. On 10 September he buys 1 ETH for £1,500 and later that day sells 1 ETH for £1,400. The sale is matched first with the ETH acquired on 10 September, even if the purchase happened after the sale, so Daniel has a £100 allowable capital loss.
The older 1 ETH remains in the Section 104 pool at £2,000. Only acquisitions made after the disposal and within the following 30 days are considered next; any balance then falls into the pool calculation.
Questions & answers
Can I offset crypto losses against income tax?
No, private investors normally offset allowable crypto capital losses against capital gains, not salary or other income. Different relief can apply only where activity genuinely amounts to a trade, which needs tailored advice.
How do I report crypto losses on Self Assessment?
Enter the total allowable losses and gains on the Capital Gains pages of your Self Assessment return. Keep the detailed transaction calculation, exchange records and wallet evidence because HMRC can ask for them later.
Can I carry crypto losses into future tax years?
Yes, unused allowable capital losses can generally carry forward after being set against gains in the year they arise. Claim them within the relevant time limit, commonly four years from the end of that tax year.
Is a crypto-to-crypto swap taxable in the UK?
Yes, swapping one cryptoasset for another is normally a CGT disposal, even if no pounds are received. Use the pound market value at the time of the swap to calculate the gain or loss.
This guidance is not a substitute for tailored advice where crypto activity may amount to a trade, where losses arise from a business, mining, staking, lending, employment income or DeFi arrangements, or where the asset is jointly owned, held by a company, in a trust, or subject to cross-border tax rules. It is also not relevant where there is no actual or claimable capital loss.
Most people holding coins or tokens personally are investors, so UK crypto capital losses are normally capital losses and cannot reduce employment income, pension income or savings income. In limited cases, however, a person’s activity may amount to a trade rather than investment. HMRC looks at the overall facts, including frequency, organisation, commercial purpose, expertise and whether the activity resembles a business; a high number of transactions alone is not decisive. If receipts and losses arise in a genuine trade, their treatment may differ from the usual HMRC cryptoasset tax approach for private investors, and trading-loss relief can involve separate conditions and restrictions.
Records should therefore identify whether each activity was undertaken personally, through a business, or by a company.
Related sources
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