Cryptoassets fell into HMRC's clear sights from 2018 onwards, and the data-sharing arrangements with major exchanges have tightened substantially since. UK investors with undisclosed crypto gains, NFT income, staking rewards, or DeFi yield need to consider voluntary disclosure now rather than later. The penalty differential between unprompted and prompted disclosure on crypto is exactly the same as for other tax: 0% to 30% versus 15% to 30% for careless behaviour. The behavioural categorisation is also consequential: HMRC treats persistent non-disclosure of substantial crypto gains as deliberate, with much heavier penalties.
This guide covers the full crypto disclosure framework. The classification of different crypto activity (CGT vs income tax). The disclosure routes available. What HMRC already knows from exchange data feeds. The treatment of NFTs, staking, and DeFi where the rules are still being settled.
Exchanges now report directly to HMRC
Major UK-accessible exchanges (Coinbase, Kraken, Binance, Crypto.com) now share customer data with HMRC under specific information notices and increasingly as a standing arrangement. The window for non-disclosure being undetected has effectively closed for substantial trading volumes. Voluntary disclosure now is materially cheaper than discovery later.
How HMRC classifies crypto activity
HMRC treats crypto activity differently depending on what it is. Most personal investing is CGT; some specific activity is income tax:
| Activity | Tax treatment |
|---|---|
| Buy-and-hold then sell | Capital Gains Tax on gains above the annual exempt amount |
| Trading frequently as a business | Income tax on profits (rare; high bar to be classified as trading) |
| Staking rewards | Income tax on the value at receipt; later sale produces CGT on gain from that base |
| Mining | Income tax on the value mined; later sale CGT on subsequent gain |
| Airdrops (passive) | Generally not taxable on receipt; CGT on subsequent disposal |
| Airdrops (in return for services) | Income tax on receipt |
| DeFi lending interest | Income tax on the receipt |
| NFT creation and sale | Generally trading income for the creator; CGT for the buyer who later sells |
Capital Gains Tax on crypto
For most personal investors, gains are CGT. The mechanics:
- 1Calculate the gain on each disposal: proceeds less acquisition cost (using the share-pooling rules HMRC mandates for crypto).
- 2Aggregate gains and losses for the tax year.
- 3Deduct the annual exempt amount (£3,000 for 2025-26, reduced from £6,000 in 2023-24 and £12,300 before that).
- 4Report on the Self Assessment return for the year, or via the Real Time Capital Gains Service for one-off significant gains.
- 5Pay CGT at 18% (basic rate) or 24% (higher rate) on the chargeable gain (rates from the October 2024 Budget).
Crypto-to-crypto trades are disposals for CGT. Selling Bitcoin to buy Ethereum is a chargeable disposal of Bitcoin even though no fiat currency moved. This catches investors who think only fiat-cash-out events are taxable.
Disclosure routes for undisclosed crypto
HMRC operates a specific Cryptoasset Disclosure Facility for taxpayers with undisclosed crypto gains or income. The structure is similar to the general DDS:
- Notify HMRC of intent to disclose. Locks in the unprompted status.
- Calculate the position: typically requires extracting historical transaction data from each exchange used.
- Submit the disclosure with calculations, supporting evidence, and proposed penalty position.
- Settle the resulting tax, interest, and penalties (or arrange Time to Pay).
The hardest part is usually the data extraction. Exchange-by-exchange transaction history can be downloaded but reconciling thousands of trades into the share-pooling format HMRC requires is non-trivial. Specialist crypto-tax software (Koinly, Recap, CoinTracking) handles the heavy lifting and produces the calculations in HMRC-compatible format.
Losses are not lost
Crypto losses can be offset against crypto gains in the same year and carried forward against future gains indefinitely. For investors with substantial losses from the 2022-23 crash, those losses have value if disclosed and registered. They cannot be claimed retrospectively years after the fact without the original year's position being filed first.
DeFi and NFTs — where the rules are still being settled
HMRC published its Cryptoasset Manual covering basic crypto in 2018-19 and updated it through 2022 to add specific guidance on staking, DeFi, and NFTs. Some areas remain ambiguous and the case law is still developing. The current HMRC position:
- Liquidity provision (depositing into AMM pools) generally treated as a disposal triggering CGT, with the LP token as the new asset.
- Yield from lending pools generally taxed as income at the value when received.
- Wrapping (e.g., ETH → wETH) treated as a disposal in HMRC's current view, though this position is contested.
- NFT minting fees added to the cost base of the NFT.
- Royalty receipts from secondary NFT sales taxed as income.
Where the position is genuinely unclear, disclosure should reflect the most reasonable interpretation with the basis documented. HMRC accepts good-faith interpretations supported by reasoning; what they do not accept is silent non-disclosure.
Undisclosed crypto gains? The disclosure window is open.
A specialist will run the historical transaction reconciliation, classify each activity correctly, identify any losses that should reduce the position, and submit the disclosure for the lowest defensible penalty band. Free initial assessment.