UK Crypto Tax Deadlines 2025/26: When to Register, File & Pay
Register for Self Assessment by 5 October 2026, file your crypto tax return by 31 January 2027, and pay in full by the same date. The thresholds are low: you must report if gains exceed £3,000 OR disposal proceeds exceed £50,000. Miss the deadline and automatic penalties kick in: £100 immediately, then £10 per day up to £900, then percentage charges at 6 and 12 months — plus interest accruing daily on any unpaid tax. This is the 2025/26 UK position.
For the 2025/26 tax year, you must register for Self Assessment by 5 October 2026 if you've never filed before or don't usually need to file. The key filing and payment deadline is 31 January 2027 — the same date applies whether you file online or on paper (though paper has an earlier deadline of 31 October). The reporting threshold is low: you must report if your capital gains exceed £3,000 OR your total disposal proceeds exceed £50,000, even if your gains are smaller.
Missing these dates triggers automatic penalties (£100 immediately, then daily charges and percentage-based surcharges), plus interest on unpaid tax. This guide walks through the exact 2025/26 dates, who must file, the reporting thresholds, and what happens if you miss the deadline.
When is the crypto tax deadline in the UK?
The UK tax year runs from 6 April 2025 to 5 April 2026 for the 2025/26 return. There are three key deadlines for Self Assessment:
1. Registration (5 October 2026): If you need to file for the first time or haven't filed before, you must tell HMRC by 5 October 2026. If you register after this date, you'll face possible penalties.
2. File online (31 January 2027): Your online Self Assessment return must reach HMRC by 11:59 pm on 31 January 2027. This is also the deadline to pay your tax in full.
3. File on paper (31 October 2026): If you're filing a paper return, HMRC must receive it by 11:59 pm on 31 October 2026 — nearly three months earlier than the online deadline.
The paper deadline is much earlier, so unless you have a strong reason to file on paper, filing online gives you an extra three months to gather your records and pay.
| Date | Action | Consequence if missed |
|---|---|---|
| 6 April 2025 | Tax year starts | n/a |
| 5 April 2026 | Tax year ends | n/a |
| 5 October 2026 | Register for Self Assessment (if you've never filed or don't usually) | Possible penalties for late registration |
| 31 October 2026 | Paper return must reach HMRC | £100 late filing penalty (immediate), then daily penalties |
| 30 December 2026 | If you want to pay via your tax code, submit by this date | Cannot use tax code; must pay in full by 31 January |
| 31 January 2027 | Online return filed AND tax paid in full | £100 late filing penalty + daily penalties + interest on late payment |
| 31 July 2027 | Second payment on account due (if applicable) | 5% penalty + interest if you don't pay |
Do I need to file a Self Assessment for crypto?
You must file a Self Assessment return if your capital gains from crypto (or any other assets) exceed the £3,000 annual exempt amount OR if your total disposal proceeds exceed £50,000, even if your gains are smaller. You must also file if you have other income that requires Self Assessment (e.g., self-employment, rental income).
The £3,000 figure is the amount you can gain without paying any tax. Above that, you owe Capital Gains Tax at 18% or 24% depending on your income. But the £50,000 threshold is separate and applies to proceeds — the total amount you sold assets for, not your profit. This means if you bought £40,000 of Bitcoin and sold it for £55,000 (a £15,000 gain), you must report because proceeds were £55,000, even though your gain is above the £3,000 allowance anyway.
If neither threshold is triggered — your gains are under £3,000 AND your total disposal proceeds are under £50,000 — you don't have to file. However, if you later do need to file for any reason (e.g., you have other income), you must report the crypto gains in that return.
Reporting thresholds: gains AND proceeds both matter
Report if EITHER your total capital gains exceed £3,000 OR your total disposal proceeds exceed £50,000. Proceeds = what you sold the crypto for, before costs. Example: sell £60,000 of crypto at a loss of £10,000 (proceeds £60,000, gain -£10,000). You must report because proceeds exceed £50,000, even though you made a loss. Losses are reported in the same return and offset future gains.
When do I register for Self Assessment?
You must tell HMRC you need to file by 5 October 2026. Register online via the HMRC Government Gateway service, or by phone on 0300 200 3300. When you register, HMRC sends you a 10-digit Unique Taxpayer Reference (UTR) number, which you'll need to file your return.
If you register after 5 October 2026, HMRC can impose a penalty. You can still file your return — HMRC will give you an alternative deadline of 3 months after your registration — but your tax is still due by 31 January 2027. So registering late doesn't extend the payment deadline; it just triggers a penalty and leaves you less time to prepare.
New traders and investors sometimes assume registration is optional or can wait until January. It's not. If you think you'll owe tax, register by October to avoid penalties and give yourself time to get your records ready.
What happens if I miss the crypto tax deadline?
HMRC imposes automatic penalties for late filing and late payment. These escalate quickly, so even a few days late can cost significantly more than the tax you owed.
Late filing penalty (missing the 31 January deadline): £100 flat penalty applies immediately, regardless of whether you owe any tax. If you're more than three months late, an additional £10 per day accrues (up to a maximum of £900). At six months late, a further penalty of 5% of the tax due or £300 (whichever is greater) applies. At 12 months late, another 5% or £300 applies.
Late payment penalty (paying after 31 January): If you file on time but pay late, a penalty of 5% of the tax unpaid kicks in at 30 days late, another 5% at 6 months late, and a third 5% at 12 months late. These are separate from the filing penalty.
Interest on late payment: In addition to penalties, HMRC charges interest on any unpaid tax from the day after the deadline. The interest rate is the Bank of England base rate + 4% (currently around 7.75%, but it changes when the base rate changes). Interest accrues daily until you pay in full.
| Days late | Penalty amount |
|---|---|
| Same day (after deadline) | £100 flat |
| 3+ months late | £100 + £10 per day (max £900 total for this tier) |
| 6+ months late | £100 + £10/day + 5% of tax due (or £300, whichever greater) |
| 12+ months late | £100 + £10/day + two lots of 5% (or £300 × 2) |
Paying on account and the 31 July deadline
If your Self Assessment bill is large, HMRC may ask you to make payments on account — essentially, to pay some tax in advance while you're waiting to file your full return. These are due on 31 January and 31 July following the end of the tax year.
For 2025/26, the first payment on account is due 31 January 2027 (the same as your main payment deadline). The second is due 31 July 2027. You'll only be asked to make payments on account if your previous year's Self Assessment bill was over £1,000.
If you make payments on account but end up owing less when you file (e.g., you had bigger losses than expected), HMRC refunds the overpayment. If you owe more, you pay the difference with your balancing payment.
CARF data reaches HMRC after you file
The Crypto-Asset Reporting Framework means UK exchanges report your transaction data to HMRC by 31 May 2027. That's four months after your Self Assessment deadline of 31 January 2027. Do not assume HMRC won't notice underreported gains — they will, once the data lands, and they'll send a "nudge" letter or demand a correction. File accurately now.
Key dates at a glance (2025/26)
- Tax year: 6 April 2025 – 5 April 2026
- Register by: 5 October 2026
- File online by: 31 January 2027
- Pay tax by: 31 January 2027
- Reporting triggers: Gains > £3,000 OR proceeds > £50,000
- Late filing penalty: £100 immediate, then £10/day, then 5% tiers at 6/12 months
- Late payment penalty: 5% at 30 days, 6 months, 12 months (separate from filing penalties)
- Interest on late payment: Base rate + 4% (accrues daily)
Next steps
Start gathering your records now. Export your transaction history from every exchange and wallet you used in 2025/26. Our free calculator imports CSV files from all major platforms and calculates your gains automatically.
Check your reporting threshold. Calculate your total capital gains and total disposal proceeds. If either exceeds the threshold (£3,000 gains or £50,000 proceeds), you must file.
Register if you haven't already. If this is your first year filing, register for Self Assessment online at GOV.UK Register for Self Assessment or call 0300 200 3300. Do this well before 5 October 2026.
Understand the SA108 form. Crypto gains go in the Self Assessment cryptoassets section, boxes 13.1–13.8. Read our detailed SA108 guide to see exactly where your figures go.
File early if you can. Filing well before 31 January gives you time to fix any errors HMRC flags and avoid the rush. The online filing system opens from 6 April 2026, so you can file as soon as you've compiled your records.
Pay on time. Set a calendar reminder for 31 January 2027 to pay your tax. If you owe £1,000 or more, HMRC will ask you for payments on account from next year (due 31 January and 31 July), so make sure you budget for that.
Sources
- GOV.UK — Self Assessment tax returns: Deadlines
- GOV.UK — Self Assessment tax returns: Penalties
- GOV.UK — Register for Self Assessment
- GOV.UK — Capital Gains Tax: Work out if you need to pay
- GOV.UK — Capital Gains Tax rates and allowances
- GOV.UK — HMRC interest rates for late and early payments
- CryptoCGT — SA108 crypto boxes 13.1–13.8 detailed guide
- CryptoCGT — How to report crypto on Self Assessment
- CryptoCGT — CARF: Crypto-Asset Reporting Framework
- CryptoCGT — Free crypto tax calculator
See your own number — free, no account
Drop your exchange CSV and read your full Capital Gains Tax figure on screen, with the Section 104 working shown. You only pay if you download the report.
Start free →This guide is information, not tax advice.Figures and thresholds are for the tax year shown (England, Wales & Northern Ireland; Scottish income tax bands differ). Rates and rules can change, and your own position may differ — check your circumstances and speak to an accountant before you file. CryptoCGT is an information tool, not a regulated tax adviser.