How to Report and Pay Capital Gains Tax on Cryptoassets

When you dispose of cryptoassets like Bitcoin, NFTs, or other tokens, you may need to pay Capital Gains Tax on any profit you make. If you haven't reported these gains to HMRC or paid the tax due, you need to either include them on your Self Assessment tax return or make a voluntary disclosure, depending on which tax years are involved.

When to use Self Assessment vs voluntary disclosure

You must report cryptoasset gains from the current tax year (2025/26) or the previous tax year on your Self Assessment tax return if you're required to file one. This is the standard route for recent disposals.

However, if you have unpaid tax on cryptoasset disposals from earlier years—meaning gains you didn't report at the time—you need to make a voluntary disclosure to HMRC. This covers transactions from older tax years that should have been declared but weren't.

Making a voluntary disclosure for unpaid tax

A voluntary disclosure is how you tell HMRC about tax you owe on cryptoassets from past years. This applies to various types of cryptoassets including exchange tokens (like Bitcoin), NFTs, and utility tokens.

If you don't contact HMRC to declare unpaid tax, you'll face additional interest and penalties on top of the tax itself.

Working out how many years to disclose

The number of years you must disclose depends on your behaviour:

If you took reasonable care but still didn't pay enough tax, you must disclose 4 years. This means you fill in the disclosure form for the 3 years before the previous tax year, and report the previous tax year and current year on your Self Assessment return by the normal deadline.

If you didn't take reasonable care, you must disclose 6 years. You fill in the disclosure form for the 5 years prior to the previous tax year, and handle recent years through Self Assessment.

If you deliberately misled HMRC, you must disclose up to 20 years. This applies when you knew you owed tax but chose not to tell HMRC, or when you knowingly submitted wrong figures on your tax return.

Information you need to gather

Before making your disclosure, collect:

• Your personal details (name, address, email, telephone number)
• National Insurance number
• Number of cryptoasset transactions
• Total proceeds or income not declared (before costs or expenses)
• Acquisition costs of the cryptoassets and any expenses
• Amount of gains or profit made (with calculations)
• Details of any cryptoasset exchanges used
• Number of cryptoassets disposed of
• Tax and interest you owe (with calculations)
• Whether you used a commercial cryptoasset calculator (and which one)

Calculating what you owe

You must work out three amounts:

Capital Gains Tax and Income Tax: Calculate your gains after deducting your annual personal allowance (the Capital Gains Tax Annual Exempt Amount). You'll need to show all your calculations.

Interest: Interest charges daily from the date tax was due until you pay it. Any additional tax in your disclosure is late and attracts interest. If you don't include the correct interest, HMRC will reject your disclosure. You can use HMRC's penalties and interest calculator to work this out.

Penalties: Penalties depend on your behaviour and how cooperative you are. Use HMRC's factsheets on penalties for inaccuracies and penalties for failure to notify to determine the appropriate penalty percentage. The penalties and interest calculator will help you calculate the final amount. On the disclosure form, explain why you've applied the penalty percentage you have—HMRC will review whether it's fair.

Dealing with cryptoassets can be complicated. You can appoint an agent to help you, or use a commercial cryptoasset calculator for your calculations.

Submitting your disclosure

You make your disclosure online through HMRC's digital service. You'll need to sign in or create sign-in details if you don't have them.

Your disclosure should include the full amount you owe: unpaid tax, penalties, and interest.

If you want an agent to submit the disclosure for you, you must give them temporary authorisation to deal with your tax.

After submitting your disclosure

HMRC will send you a payment reference number once they receive your disclosure. This is a 14-character reference starting with X. If you don't receive it within 15 working days, contact the HMRC helpline.

After HMRC checks your disclosure, they will either send you a letter confirming they've accepted your offer, or contact you to say they cannot accept it. They may ask for evidence to complete their checks—if you don't provide the information needed, your offer might not be accepted.

If HMRC's checks show you knowingly gave incorrect information, they may investigate your tax affairs further and you could face higher penalties.

Paying what you owe

You must pay the full amount within 30 days of making your disclosure. Use your 14-character reference number when paying—using an incorrect reference will delay allocation of your payment.

If the deadline falls on a weekend or bank holiday, your payment must reach HMRC by the end of the previous working day. Missing the deadline means you may face additional penalties and interest.

Payment methods

Pay online: You can approve a payment through your online bank account or pay by debit or corporate credit card. You cannot use a personal credit card. Corporate credit and debit cards carry a non-refundable fee.

Online bank payments are usually instant but can take up to 2 hours to show in your account.

Pay by bank transfer:

For UK bank accounts:

• Sort code: 08 32 10
• Account number: 12001020
• Account name: HMRC Shipley

For overseas bank accounts:

• IBAN: GB03 BARC 2011 4783 9776 92
• BIC: BARCGB22
• Account name: HMRC Shipley

You must make all payments in pound sterling.

CHAPS or Faster Payments arrive the same or next working day. Bacs takes 3 working days. Check your bank's processing times and transaction limits before paying.

If you cannot pay the full amount

You should pay the full amount when you make your disclosure. If you genuinely cannot pay, contact HMRC as soon as you have your payment reference number on 03000 55 22 94 (Monday to Thursday 9am to 5pm, Friday 9am to 4:30pm).

HMRC may discuss and agree a new payment arrangement. Be ready to provide:

• Your payment reference number
• How and when you think you can pay
• Your current weekly or monthly income and outgoings
• Details of your assets (home, other property, vehicles, investments, bank balances)
• What you owe (mortgages, loans, credit cards)

Sources

• Tell HMRC about unpaid tax on cryptoassets
• Pay tax on cryptoassets

This article provides general guidance based on current HMRC rules. For advice specific to your situation, speak to your accountant.