Many UK cryptocurrency investors are uncertain about their tax obligations — particularly those who have never sold their crypto for pounds. In this guide we answer the most common questions about declaring crypto to HMRC and explain exactly what you need to report in 2026.
Do You Have to Tell HMRC About Your Crypto?
Yes — if you have made taxable gains or received crypto income above the relevant thresholds, you are legally required to declare it to HMRC through a Self Assessment tax return. Failing to declare crypto gains is tax evasion — a serious criminal offence.
HMRC has been actively enforcing crypto tax compliance since 2019. It has obtained bulk transaction data from UK crypto exchanges and has sent thousands of nudge letters to taxpayers suspected of having undeclared crypto gains.
When Do You Need to File a Self Assessment?
You need to file a Self Assessment tax return if your total capital gains in a tax year exceed your annual Capital Gains Tax exempt amount, your total income from all sources exceeds 100,000 pounds, you received crypto as income from staking, mining, or employment, or you have not previously registered for Self Assessment and have taxable crypto activity.
What If You Have Not Sold Any Crypto?
Simply holding cryptocurrency — buying it and not selling — does not trigger any tax. There is no wealth tax on unrealised crypto gains in the UK. You only become liable for Capital Gains Tax when you dispose of your crypto — by selling, trading, spending, or gifting it.
What Crypto Activity Does HMRC Know About?
HMRC has significant data collection powers and has used them extensively in the crypto space. It has obtained customer data from major UK and international crypto exchanges including Coinbase, eToro, and Binance. This data includes transaction histories and customer identification information.
Do not assume HMRC is unaware of your crypto activity. The safer and legal assumption is that HMRC can access your exchange transaction history.
What Happens If You Have Not Declared Previous Crypto Gains?
If you have made taxable crypto gains in previous tax years that you have not declared, the best course of action is to make a voluntary disclosure to HMRC as soon as possible. HMRC treats voluntary disclosures far more favourably than cases where it discovers undeclared income independently — penalties are typically much lower and criminal prosecution is less likely.
HMRC’s Cryptoassets Manual provides detailed guidance on its approach to crypto taxation. Consulting a tax adviser with crypto expertise is strongly recommended for anyone with significant undeclared historic gains.
How to Declare Crypto on Your Self Assessment
Log in to your HMRC online account and complete your Self Assessment tax return. Capital gains from crypto are reported in the Capital Gains Summary section. Income from staking, mining, or airdrops is reported in the Additional Information section as miscellaneous income.
Use crypto tax software like Koinly to generate HMRC-compatible reports that make completing your Self Assessment significantly easier.
Key Takeaways
- UK crypto investors with taxable gains or income must declare them to HMRC through Self Assessment
- HMRC has obtained transaction data from major crypto exchanges — assume your activity is known
- Simply holding crypto without selling does not trigger any tax obligation
- If you have undeclared historic gains, make a voluntary disclosure to HMRC as soon as possible
- Use Koinly to generate HMRC-compatible tax reports for your Self Assessment
- Consult a tax adviser with crypto expertise for significant or complex crypto tax situations