When to report crypto on UK Self Assessment: deadlines and penalties
UK crypto tax deadlines for 2026: tax year 6 April – 5 April, paper deadline 31 October, online 31 January. Penalties, real-time CGT rules, registration timing.
The UK tax year runs 6 April to 5 April, and crypto disposals are reported annually on Self Assessment with the figures due online by 31 January following the end of the tax year. Paper filers must submit by 31 October. Unlike UK property, crypto does not require 60-day real-time CGT reporting — once a year is the rule.
When do I report crypto to HMRC?
The UK tax year explained
The UK tax year is a quirk: 6 April to 5 April. So the 2025/26 tax year is the period from 6 April 2025 to 5 April 2026. Disposals on or after 6 April 2026 fall into 2026/27.
For crypto, the date that matters is the date of disposal (which for an exchange trade is normally the trade date, not the GBP withdrawal date). A market sell placed at 23:50 on 5 April 2026 and confirmed at 23:55 the same day is in 2025/26. A sell placed at 00:01 on 6 April 2026 is in 2026/27.
If you're running a year-end loss harvest, double-check your exchange's settlement timestamps. The order timestamp and the settlement timestamp can differ on busy days, and HMRC takes settlement as the disposal date.
Filing deadlines: 31 October and 31 January
Two deadlines for the same tax year, depending on how you file:
- 31 October following the end of the tax year — paper filing. Almost nobody files a crypto Self Assessment on paper because the SA108 and supporting working papers are tedious to copy by hand.
- 31 January following the end of the tax year — online filing via gov.uk Self Assessment or commercial filing software. This is the deadline that matters for most crypto investors.
The tax payment deadline is the same as the online filing deadline: 31 January. If you owe £4,000 of CGT for 2025/26, the £4,000 is due by 31 January 2027. Interest accrues on unpaid balances from 1 February.
Payments on account (50% of last year's liability paid each in January and July) generally do not apply to capital gains — they apply to income tax and Class 4 NICs. CGT is paid in full at filing.
Self Assessment registration deadline
If you don't already file Self Assessment, you must register by 5 October following the end of the tax year in which the filing requirement was triggered. So a crypto disposal triggering CGT in 2025/26 means register by 5 October 2026.
Registration is at gov.uk/register-for-self-assessment. HMRC posts a Unique Taxpayer Reference (UTR), typically arriving within 10 working days. You then create a Government Gateway account and link the UTR. Without the UTR you can't file online — register early.
Failing to register on time triggers a separate "failure to notify" penalty, distinct from the late-filing penalty. It's typically a percentage of the tax owed, escalating with how late you are and whether HMRC considers the failure deliberate.
Late-filing penalties
HMRC's penalty schedule applies even if no tax is due:
| How late | Penalty |
|---|---|
| Day 1 (1 February) | £100 fixed |
| 3 months late | £10/day up to 90 days (£900 max) |
| 6 months late | £300 or 5% of tax due, whichever is higher |
| 12 months late | Another £300 or 5% |
Interest accrues on unpaid tax from 1 February at the HMRC rate (currently around 7.75% per annum). Plus a separate late-payment penalty: 5% at 30 days late, 5% at 6 months, 5% at 12 months.
A modest crypto gain late-filed for two years can easily turn a £200 CGT bill into a £1,500+ total liability. File on time even if you can't pay — the late-payment penalties are smaller than the late-filing ones.
Real-time CGT and crypto
UK residential property disposals require real-time CGT reporting within 60 days of completion via a separate return on gov.uk. This was introduced in 2020 and remains specific to property — it does not apply to crypto.
Crypto disposals, no matter the size, are reported annually on Self Assessment. A £500,000 BTC disposal in May 2025 is reportable on the 2025/26 Self Assessment due 31 January 2027 — there's no separate real-time return.
That can cut both ways. The cash for the tax bill needs to be available 18+ months after the disposal — easy if you've set it aside, painful if you've redeployed the proceeds and the price has tanked since.
Summary
UK tax year: 6 April to 5 April. Self Assessment online filing deadline: 31 January following the year-end. Paper deadline: 31 October. Registration deadline: 5 October. No real-time CGT for crypto. Penalties escalate quickly — file on time even if you can't pay yet.
For when crypto actually triggers a filing requirement, see do I have to file Self Assessment. For the form itself, see SA108 for crypto. The full rulebook is in our UK crypto tax guide. HMRC's deadline page is at gov.uk/self-assessment-tax-returns/deadlines.
Frequently asked questions
When does the UK tax year for crypto start and end?
The UK tax year runs from 6 April to 5 April the following year. Crypto disposals between those dates form one tax year. Settlement date matters — a sale order placed on 5 April but settling on 6 April lands in the new tax year.
What is the deadline for reporting crypto on Self Assessment?
31 January following the end of the tax year for online filers (so 31 January 2027 for the 2025/26 tax year). Paper filers must submit by 31 October — virtually no one files crypto Self Assessment on paper. Tax due is also payable by 31 January.
Is there a real-time reporting requirement for crypto like for property?
No. Crypto disposals are reported annually on the Self Assessment, not within 60 days like UK residential property. The 60-day real-time CGT rule only applies to property disposals — crypto does not trigger it, even on very large gains.
What if I miss the 31 January deadline?
An immediate £100 late-filing penalty, even if no tax is due. After 3 months: £10 per day up to 90 days (£900 maximum). At 6 months: £300 or 5% of tax owed (whichever is higher). At 12 months: another £300 or 5%. Interest accrues on unpaid tax from 1 February.
When do I need to register for Self Assessment for crypto?
By 5 October following the end of the tax year. So if you triggered a filing requirement in 2025/26, register by 5 October 2026. The UTR can take up to 10 working days to arrive — register early to leave room for the file-by-31-January deadline.
Les videre
When crypto triggers a UK Self Assessment in 2026: £3,000 CGT allowance, £50,000 disposal proceeds threshold, staking and trading allowance rules.
When must UK investors report crypto to HMRC in 2026? Disposals over £50,000, gains over £3,000, trading vs investing, and what CARF data sharing means for you.
Step-by-step guide to filing crypto on HMRC Self Assessment in 2026: log in, tailor the return, complete SA108 boxes 14-22, attach computation, and submit by 31 January.
How to complete SA108 for crypto in 2026: box-by-box breakdown of disposals, proceeds, costs, gains and losses, plus the working sheet HMRC expects.
How to report crypto on UK Self Assessment in 2026. Step-by-step from cost basis through CGT to SA108, with 2026 allowances and worked examples.