# Crypto capital losses in the UK — claiming and carrying forward

Allowable crypto capital losses can reduce capital gains; claim and retain evidence of unused losses for future years. They do not offset salary. Theft and lost keys are not themselves disposals. A negligible-value claim has separate conditions.

## Key facts
- Losses must be claimed — they are not automatic.
- Same-year losses offset same-year gains first.
- Carry forward indefinitely until used.
- Negligible value claims possible if asset becomes worthless.
- Bed and breakfast rules limit artificial loss creation.

## Calculating a capital loss

Calculate the loss using the allowable cost matched to the disposal, less its proceeds. Apply same-day and 30-day matching before the Section 104 pool; selling below the pooled average does not by itself establish the allowable loss.
## Using losses in the tax year

Net losses against net gains. If overall net loss, no CGT due — report the loss on SA108 to preserve carry forward.
## Carrying forward

Unused losses roll to future tax years and offset future gains. Keep SA108 submissions as proof.
## Lost, stolen or worthless tokens

Theft is not a disposal and does not itself create a CGT loss. Permanently inaccessible tokens and tokens that become worthless require a separate negligible-value assessment. Keep evidence of ownership, acquisition and the loss of value or access.

Use the [loss-evidence and negligible-value checklist](https://digital-assets.co.uk/tax/crypto-negligible-value-claims/) to distinguish the routes before making a claim.
## Tax-loss harvesting caution

Repurchases of the same token within 30 days can change the acquisition cost matched to a disposal. Model the actual transactions and matching sequence before assuming that a sale creates a particular loss.

Review the [30-day matching example](https://digital-assets.co.uk/tax/pooling-section-104-rules/) before assuming that selling and repurchasing creates the expected loss.

## FAQs
### Can I offset crypto losses against salary?

No. Capital losses offset capital gains only, not Income Tax on employment.

## Sources

- [HMRC — Theft and fraud](https://www.gov.uk/hmrc-internal-manuals/cryptoassets-manual/crypto22450)
- [HMRC — Lost private keys](https://www.gov.uk/hmrc-internal-manuals/cryptoassets-manual/crypto22400)
- [HMRC — Capital Gains Tax losses](https://www.gov.uk/capital-gains-tax/losses)
- [HMRC — Cryptoassets Manual](https://www.gov.uk/hmrc-internal-manuals/cryptoassets-manual)

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— Digital Assets UK (https://digital-assets.co.uk/tax/crypto-losses-and-harvesting/), reviewed 2026-09-30. Source: https://www.gov.uk/hmrc-internal-manuals/cryptoassets-manual/crypto22450