Crypto Loss Claim HMRC 2026: how to offset and carry forward

A crypto loss is only useful if HMRC knows about it. UK rules let you offset losses against gains in the same tax year, carry the excess forward indefinitely, and even claim a loss on assets that have become worthless without selling. Miss the four-year reporting window, though, and the loss disappears. The 2025-26 Annual Exempt Amount of £3,000 makes loss tracking more important than it has been for a decade.

How do you claim a crypto loss in the UK?

In-year loss offset

Losses crystallised in the same tax year as your gains offset those gains automatically. No election is needed. HMRC requires you to use in-year losses fully before the Annual Exempt Amount (£3,000 for 2025-26) is applied, which can sting: the AEA is wasted if your gains are already below it after losses.

Order of offset matters less than the offset itself, because the rate on the remaining gain is the same once you exceed the AEA. Crypto losses can offset gains on any other chargeable asset (shares, second properties at the residential CGT rates, business assets) because they all sit within the same Capital Gains Tax pool.

Carry forward and the 4-year rule

Losses that exceed gains in the year carry forward indefinitely. There is no time limit on their use, but there is a hard limit on when you can register them. The loss must be reported to HMRC within four years of the end of the tax year in which it arose.

Practically this means putting losses on the SA108 of the year they crystallise, even if you have no gains to offset against. The £4,500 of unused losses then sits in your carry-forward pool ready for future years. If you forget, you have until 5 April four years later to make a stand-alone written claim. After that, the loss is permanently lost.

Negligible value claims

Section 24 TCGA 1992 allows you to claim a loss on an asset that still technically exists but has become worthless. You do not need to sell. The claim treats the asset as if you had sold it for nothing on the date you make the claim (or up to two years earlier, if you owned it then and it was already negligible).

For crypto, this typically applies to rugpulled tokens, abandoned projects with dead contracts, or worthless coins from defunct exchanges where recovery is nil. Submit a written claim to HMRC including: the asset, the cost basis, the date you claim it became negligible, and the evidence that supports negligibility.

HMRC publishes a list of agreed negligible value securities for traditional shares; there is no equivalent crypto list. Each crypto claim is decided on its facts. Keep on-chain evidence (zero-volume snapshots, contract abandonment, founder departures, exchange delisting notices) ready.

Lost coins and lost wallets

Lost private keys are a frequent claim category. HMRC's published view (CRYPTO22600) is that the asset legally still exists on-chain, so the loss of access alone is not a disposal. The route to relief is a negligible value claim, on the basis that the lost keys make recovery impossible and the asset's economic value to you is nil.

Document everything: the wallet address, the device or seed it was held on, the recovery attempts you made (recovery service receipts, professional ethical-hacking reports), and the dates. The strength of your negligible value claim depends entirely on the strength of this evidence.

Exchange failures: FTX and beyond

FTX (November 2022), Celsius (July 2022), Voyager and BlockFi created a wave of UK loss claims. HMRC's accepted approach is that a loss arises when the recovery amount is determined through the bankruptcy process, not when the platform freezes withdrawals. At that point, your loss equals cost basis less the determined recovery.

Where the bankruptcy process drags on for years, two routes exist. Wait for the final recovery determination and book the loss in the year it becomes certain. Or, if recovery is genuinely nil and you want to crystallise sooner, file a negligible value claim supported by the bankruptcy filings. The FTX estate's recovery turned out to be much higher than initially expected; aggressive early claims have had to be revised on later returns.

Loss harvesting and the 30-day rule

Loss harvesting is selling at a loss to bank a deductible loss, typically near the tax year end. UK rules permit it but counter the obvious abuse with the bed-and-breakfast rule. A disposal is matched first against same-day acquisitions, then against acquisitions within the next 30 days, and only then against the Section 104 pool. Buy back the same coin within 30 days and the loss is neutralised against the matched lots.

The legitimate workarounds are simple. Wait 31 days before rebuying. Switch to a related but distinct asset for the 30-day window (BTC to ETH, then back). Or use a no-gain no-loss spousal transfer to retain household exposure while crystallising the loss personally. See our 30-day rule guide for the full mechanics.

Worked example: harvesting and offsetting

Sara has held SOL and BTC across the 2025-26 tax year. Her positions and disposals look like this.

Net gains of £1,700 sit inside the £3,000 Annual Exempt Amount, so Sara owes no CGT for the year. She still reports each disposal on SA108 because total proceeds exceeded the reporting thresholds and she made a negligible value claim that needs to be on record. If she had skipped the SOL sale and kept holding, her £4,400 BTC gain would have produced £336 of tax (£1,400 above the AEA at 24%). The harvested SOL loss saved that bill in cash and preserved future flexibility.

Scam and fraud losses

Losing crypto to a phishing site, a fake exchange or a romance scam is one of the saddest and most legally complex loss categories. The default HMRC view is that a fraud-induced transfer is a disposal at the value transferred, not a loss, because you parted with the asset voluntarily, however manipulated the consent.

The route to relief is normally a negligible value claim on whatever residual asset you hold, plus a clear evidence trail of the fraud (police crime reference number, Action Fraud report, bank correspondence, exchange security ticket numbers). Some fraud cases have been accepted as theft rather than disposal, which gives a cleaner loss treatment, but the burden of proof is high and HMRC rarely concedes without contemporaneous documentation.

NFT losses

NFT losses follow the same Capital Gains framework as fungible-token losses but the valuation difficulty is higher. Where an NFT collection has crashed and there is little on-chain volume, a sale at the floor price (even £1) is a clean realisation. Where there is no buyer at any price, a negligible value claim is the only practical route, supported by trading-volume snapshots from OpenSea or Blur and any contract renouncement evidence.

Because NFTs are non-fungible, each piece is its own asset for cost basis purposes. There is no Section 104 pool to average across an NFT collection. Track each NFT separately and claim the loss on the specific item, not on a portfolio basis.

Capital losses versus trading losses

For 99% of UK retail crypto investors the loss is a capital loss, claimable only against capital gains. The rare exception is HMRC-recognised crypto trading, where losses sit within the income tax framework and can offset other income (sideways loss relief, subject to caps).

HMRC's published view in CRYPTO20250 is that the badges-of-trade test is hard to meet for crypto. Frequent trading alone is not enough. The activity needs commercial scale, organisation, and the hallmarks of a business: dedicated infrastructure, a written strategy, professional record keeping, and ideally separate financial flows. Almost no retail investor passes that bar, and HMRC's default assumption is capital treatment.

Trying to argue trading status to unlock sideways loss relief is risky. If HMRC rejects the position, you face the loss disappearing into the CGT pool plus penalties for an incorrect return. The conservative path is to stay capital, claim the loss properly on SA108, and use it against future gains.

Reporting losses on SA108

Capital losses go on SA108. Box 17 captures total losses for the year, box 47 captures the loss carry forward from earlier years, and the white space lets you add detail. For crypto, list aggregated proceeds, allowable costs, the resulting loss, and the number of disposals. Brief asset descriptions are enough; the underlying transaction list stays in your records.

Negligible value claims should be flagged in the white space with the asset name, the deemed disposal date, the cost basis, and a brief rationale (project abandoned, contract renounced, recovery determined nil, exchange in liquidation). Lost-wallet claims need similar treatment plus a sentence on the recovery attempts made.

Where the loss is your only entry on SA108, file a return anyway. You cannot carry forward an unreported loss and HMRC will not automatically pick it up from the CARF data exchange. The four-year window starts from the end of the tax year of disposal, not from the end of the tax year you eventually use the loss.

2026 thresholds and rates

The 2025-26 Annual Exempt Amount is £3,000. Gains above that are taxed at 18% within your basic rate band and 24% above. The same rates apply across crypto, shares and most other chargeable assets after the rate alignment in October 2024. Residential property still has its own 18% and 24% bands.

Losses brought forward from earlier years are deducted after the AEA, not before. This is the opposite of in-year losses, which must be used in full before the AEA. The asymmetry rewards reporting losses promptly: a loss carried forward will not waste the AEA, but a loss in the same year as a small gain can.

Summary

Crypto losses are valuable only if you bank them properly with HMRC. Realised losses offset same-year gains automatically, excess carries forward indefinitely if reported within four years, and negligible value claims unlock relief on worthless tokens without a sale. Lost wallets are claimable but only with strong evidence. Exchange-failure losses crystallise on bankruptcy recovery determination. The £3,000 Annual Exempt Amount has made loss harvesting more relevant than at any time since the AEA was first reduced.

For the broader UK framework see our UK Crypto Tax 2026 guide and learn the 30-day bed-and-breakfast rule before any year-end harvest. To run the maths across a full transaction history see how to calculate crypto taxes. HMRC's reference is at gov.uk Capital Gains Manual CG15800.