Crypto capital losses in the UK are not automatically tax-relievable: HMRC usually needs a disposal or valid negligible-value claim, calculated in GBP and supported by evidence.
When a crypto loss is allowable for UK CGT
A crypto loss is normally allowable only following a disposal or a valid negligible value claim; a price fall while you still own the asset is usually an unrealised loss.
A falling price is not enough
Holding 1 BTC bought for £30,000 when it is worth £18,000 does not itself create an allowable £12,000 loss. If you sell it for £18,000, subject to HMRC matching rules, the sale can create a capital loss.
Sales, swaps and gifts can be disposals
Selling crypto for pounds, swapping Ethereum for Solana, spending tokens, or gifting tokens to most people can all be disposals. Transfers between wallets you own are usually not disposals because ownership has not changed.
Decision tree for difficult losses
Use this test before entering a loss on your return:
- Still holding after a price crash: no disposal, so normally no claim yet.
- Sold for GBP, euros or dollars: calculate the gain or loss in GBP.
- Swapped one token for another: calculate a disposal in GBP on the swap date.
- Token is genuinely worthless: consider a negligible value claim if HMRC's conditions are met.
- Exchange insolvency, such as FTX or Celsius: do not assume insolvency itself creates a disposal.
- Hack, scam, theft or lost private key: preserve proof and seek advice before claiming.
- Lending, staking or locked DeFi assets: check the contract and token movements, as tax treatment can turn on the facts.
- Sent to a burn address: this may be a disposal, but keep the transaction hash and purpose.
Treat difficult cases as evidence-led rather than automatic losses. An exchange insolvency, including an FTX or Celsius-style failure, may leave you with a claim against the platform that still has value, so insolvency alone is not necessarily a crypto disposal. A lost private key tax claim is similarly uncertain because inaccessible tokens may still exist; a crypto scam loss may instead involve a disposal for what was received, if anything. A delisted token is not automatically worthless if it can still be transferred or traded elsewhere, while a transfer to a burn address may be a disposal and should be supported by the transaction hash and purpose.
For lending or staking, establish whether beneficial ownership changed and whether a return right remains. A negligible value claim needs the statutory conditions and credible evidence that the asset has become of negligible value. For 2026, check current HMRC guidance, CGT rates and the annual exempt amount before filing, because those figures can affect tax due even where the basic disposal and matching rules have not changed.
HMRC matching rules change your GBP loss
HMRC applies the same-day rule, then the 30-day rule, and finally the Section 104 pool when calculating the GBP result of a crypto disposal.
If 2 ETH in a Section 104 pool have a total allowable cost of £4,000, their average pooled cost is £2,000 each. You cannot normally select a £2,800 purchase simply because it would generate a larger loss.
A GBP matching example
All transactions must be translated into pounds sterling on the relevant date using a consistent, supportable exchange-rate source.
| Transaction | Date | GBP amount | HMRC match | Result |
|---|
| Section 104 pool: 1 BTC | Before 10 May | Cost £24,000 | Used only after later matches | Pool remains available |
| Sell 0.50 BTC | 10 May | Proceeds £13,000 | First disposal to match | Await later purchases |
| Buy 0.20 BTC | 10 May | Cost £5,600 | Same-day rule | £400 loss on 0.20 BTC |
| Buy 0.30 BTC | 25 May | Cost £8,400 | 30-day rule | £600 loss on 0.30 BTC |
| Total disposal | 10 May | Proceeds £13,000 | No Section 104 amount used | Total loss £1,000 |
Fees can change the answer
Directly attributable acquisition and disposal fees can usually be included, while general subscriptions and personal-security costs normally cannot.
HMRC loss calculation order
1. Same day
Tokens bought that day
→
2. Next 30 days
Later acquisitions first
→
3. Section 104
Average pooled cost
Calculate proceeds less matched cost and directly related fees. The result is a gain or allowable loss in GBP.
A single disposal can be split across all three matching stages. For example, assume you sell 1 BTC for £20,000. You buy 0.20 BTC later that same day for £4,600, buy 0.30 BTC 15 days later for £6,900, and the remaining 0.50 BTC is matched with a Section 104 pool whose average cost is £15,000 per BTC. Allocate the £20,000 proceeds by quantity: £4,000 to the same-day amount, £6,000 to the 30-day amount and £10,000 to the pool amount. The same-day rule produces a £600 loss, the 30-day rule produces a £900 loss, and the pool portion produces a £2,500 gain (£10,000 less £7,500).
The overall GBP crypto calculation is therefore a £1,000 gain before directly related fees. The same order applies to a crypto swap tax calculation: the sterling market value of the token received normally determines the disposal proceeds.
Claim crypto losses through self assessment
Report an allowable loss in the CGT section of Self Assessment, or make a separate claim where no return is required.
Entering the loss and making a claim
A disposal on 20 March 2026 falls in the 2025 to 2026 tax year. Capital loss claims normally must reach HMRC within four years from the end of the tax year in which the loss arose.
Keep records HMRC can test
Keep exchange histories, wallet hashes, GBP values, fee records, bank evidence and correspondence relating to insolvencies, hacks or scams.
📦
Available on Amazon
A current UK crypto tax reference book can help when you need to reconcile exports, wallet transfers and HMRC terminology. Treat it as a checking aid, not a substitute for advice on an insolvency or fraud loss.
- Explains UK CGT terms such as disposals, pooling and allowable costs in one place
- Helps compare exchange transaction histories with figures entered on Self Assessment
- Provides a useful paper reference when checking records before the 31 January deadline
Search on Amazon →
Losses reduce gains, not wages
Allowable capital losses generally reduce capital gains, not salary, rental profit, savings interest or other Income Tax income. Unused losses can generally carry forward if claimed.
Check the facts before submission
Rules and reporting fields can change between tax years, and fraud, insolvency, lending, staking and inaccessible wallets need careful fact-based analysis.
This guidance is not enough on its own if you are not UK tax resident, trade through a company, run a trading business, receive tokens as income, or use complex DeFi. Seek qualified UK tax advice where a loss involves fraud, insolvency, lending, staking, stolen assets, lost private keys or uncertain ownership rights.
For HMRC tax purposes, keep a calculation for each allowable capital loss showing the disposal date, asset and quantity, GBP proceeds, matched acquisition costs, fees and the resulting figure.
- Enter the total in the Capital Gains Tax pages of your UK tax return when you file Self Assessment. If you do not need to file a return, a separate written claim to HMRC should identify you, the tax year, the amount claimed and the calculation and records supporting it
- It must normally be made within four years of the end of that tax year. Losses of the year reduce gains of the same year before the annual exempt amount is applied. For example, £7,000 of gains less a £2,500 crypto loss leaves £4,500 of net gains
- For 2025/26, a £3,000 annual exempt amount would leave £1,500 taxable
Brought-forward losses are generally used only to reduce later net gains above the annual exempt amount, helping to preserve losses that are not yet needed.
Common questions
Are crypto losses tax deductible in the UK?
Allowable crypto capital losses can reduce capital gains, but not normally Income Tax.
Can I claim a loss because Bitcoin crashed?
No. A crash alone is not an allowable loss while you still own the Bitcoin.
Can I offset crypto losses against Income Tax?
No, private-investor crypto capital losses normally offset capital gains rather than Income Tax income.
How long do I have to claim a crypto loss?
You normally have four years from the end of the relevant tax year.
Is an FTX or Celsius loss automatically allowable?
No, because recovery rights and the precise legal position can affect whether a claim is possible.
What records do I need for HMRC crypto losses?
Keep trade dates, token amounts, GBP values, fees, wallet hashes and exchange records.
The essential points:- A market fall is not normally a tax loss until a disposal or valid negligible value claim exists.
- Same-day and 30-day acquisitions can override the Section 104 pool and reverse an expected result.
- Claimed losses usually reduce capital gains, not Income Tax, and unclaimed losses can miss the four-year deadline.
- For scams, insolvencies, lending and lost access, preserve evidence first and obtain advice before reporting a loss.
Related sources
These articles can help you explore the topic in more depth:
