UK Crypto Tax Deadline 2025-26
The 2025-26 tax year runs from 6 April 2025 to 5 April 2026. The key deadlines for Self Assessment filing are 5 October 2026 (notify HMRC if you need to register), 31 October 2026 (paper return), and 31 January 2027 (online filing and payment). Miss the January deadline and HMRC charges an automatic £100 penalty - even if you have no tax to pay.
2025-26 deadlines at a glance
| Tax year | 6 April 2025 - 5 April 2026 |
| Notify HMRC | 5 October 2026 (if not already in Self Assessment) |
| Paper return | 31 October 2026 |
| Online filing deadline | 31 January 2027 |
| Payment deadline | 31 January 2027 |
| What to file | Self Assessment with SA108 (capital gains) and SA100 (staking or mining income) |
Calculate your UK crypto taxes now. Upload your exchange CSV, select United Kingdom, and get a free preview with Section 104 gains, losses, and staking income calculated automatically. No sign-up required.
Try the UK Crypto Tax Calculator - free →Key dates for the 2025-26 tax year
These are the critical dates for UK crypto tax filers covering the 2025-26 tax year.
- 6 April 2025: 2025-26 tax year begins. Any crypto disposals from this date fall in the new year.
- 5 April 2026: 2025-26 tax year ends. All disposals between 6 April 2025 and this date need to be reported.
- 5 October 2026: Deadline to notify HMRC that you need to file a Self Assessment return for 2025-26, if you were not already registered. Missing this date means a separate penalty exposure on top of any filing penalty.
- 31 October 2026: Paper Self Assessment deadline. Online filing is almost always preferable.
- 31 January 2027: Online Self Assessment filing deadline. All tax owed for 2025-26 is also due on this date.
- 30 days after 31 January 2027: A 5% late-payment penalty may apply to tax still unpaid at that point. Further penalties apply at six and twelve months after the payment deadline.
What you need to file by the deadline
Pulling together the right data is the part most filers underestimate. Here is what you need before you sit down with your Self Assessment.
- Full exchange CSV export - all time, not just 2025-26. Section 104 pooling requires your complete acquisition history. A purchase made in 2019 affects the pool cost for disposals in 2025-26.
- EVM wallet addresses if you used DeFi, NFTs, or held crypto in a non-custodial wallet on Ethereum, Polygon, Arbitrum, or other chains.
- Bitcoin wallet addresses if you held BTC in hardware wallets or other self-custody addresses not captured in your exchange CSV.
- Section 104 pool calculations for each asset disposed of during 2025-26, with same-day and bed-and-breakfast matching applied in the correct order before the pool average is used.
- Staking and earn income figures for your SA100. These are reported as miscellaneous income at the sterling value on the date each reward was received, if the activity does not amount to a trade.
- SA108 Capital Gains Summary - specifically the Cryptoassets section: number of disposals, total proceeds, total allowable costs, and net gains or losses.
How to calculate your crypto taxes before the deadline
Manual Section 104 calculations across multiple assets and years are time-consuming and error-prone. Here is how to get it done quickly.
- Export your full transaction history. Log into each exchange and download your complete CSV - select "All time" as the date range, not just 2025-26. Older acquisitions affect your current pool costs.
- Upload to DYOR.tax and select United Kingdom. The Section 104 engine handles same-day matching, bed-and-breakfast 30-day matching, and weighted average pooling automatically.
- Add wallet addresses if relevant. If you used DeFi or held crypto on-chain, add your EVM or Bitcoin addresses. Transactions are merged with your exchange data, with duplicate detection for transfers between your own accounts.
- Review your free preview. You see your capital gains, capital losses, staking income, and top assets by P&L before paying anything. All values are converted to GBP using historical rates.
- Download the full PDF report. It maps every figure to the correct SA108 box - number of disposals, total proceeds, allowable costs, gains or losses - with step-by-step filing instructions. Enter these directly into your Self Assessment return.
What happens if you miss the deadline
HMRC applies penalties automatically. The £100 charge applies the day after the deadline regardless of your circumstances.
- Day 1 late: Automatic £100 fixed penalty. Applies even if you have no tax to pay and even if you file the next day.
- 3 months late: £10 per day for each subsequent day, up to a maximum of £900 (90 days at £10).
- 6 months late: Additional penalty of 5% of the tax due, or £300 - whichever is greater.
- 12 months late: A further 5% or £300, again whichever is greater. In cases where HMRC believes you deliberately withheld information, this penalty can rise significantly.
- Interest on unpaid tax: Accrues daily from 1 February 2027 at the HMRC late payment rate on any unpaid amount.
If you have already missed the January 2027 deadline, file your return now rather than waiting. The daily £10 penalties run for 90 days from the three-month mark - stopping the clock by filing is always the right move, even if you cannot pay the full amount immediately.
CGT rates for 2025-26
Capital Gains Tax rates on crypto disposals changed on 30 October 2024 and apply in full for the 2025-26 tax year.
- Basic rate taxpayer: 18% on crypto gains
- Higher or additional rate taxpayer: 24% on crypto gains
- Annual Exempt Amount: £3,000 for 2025-26 - gains below this are tax-free
- Band interaction: Your total taxable income and capital gains share the basic rate band (£50,270 for 2025-26). If your income uses up part of the band, the remaining allowance determines whether your gains are taxed at 18% or 24%.
Losses made in 2025-26 can be set against gains in the same year or carried forward to future years. Report losses even if you have no gains to offset - they must be claimed within four years of the end of the tax year in which they arose.
If you claimed the new four-year Foreign Income and Gains regime (available from 6 April 2025 for qualifying new UK residents), you do not benefit from the Annual Exempt Amount for any year in which that election applies. Consult a tax adviser if this may affect you.
CARF and what it means for UK crypto users
The Cryptoasset Reporting Framework came into force in the United Kingdom on 1 January 2026 under the Reporting Cryptoasset Service Providers (Due Diligence and Reporting Requirements) Regulations 2025. UK cryptoasset service providers - exchanges, custodians, and similar platforms - are now required to collect customer tax-residence and transaction data.
The first reporting window runs from 1 January 2027 to 31 May 2027, covering the calendar year 1 January 2026 to 31 December 2026. HMRC may receive reportable user and transaction data from in-scope UK providers under CARF rules. Users who fail to provide accurate information to a UK provider can face penalties.
This does not change your filing obligations directly - you were always required to report crypto gains through Self Assessment. It does mean that HMRC will have a growing body of third-party data available for cross-referencing from 2027 onwards.
Common reasons UK crypto filers miss the deadline
- Waiting for exchange tax reports that do not exist. UK crypto exchanges do not issue a tax form equivalent to the US 1099-DA. You need to export your own CSV and calculate your gains. Nothing arrives in the post.
- Not realising on-chain activity needs to be included. If you used DeFi on Ethereum, held NFTs, or received staking rewards to a non-custodial wallet, that activity may create taxable events and should be reviewed and included where relevant alongside your exchange history.
- Underestimating how long Section 104 calculations take manually. Computing pool cost across multiple assets, applying the same-day and bed-and-breakfast rules in the correct order, and converting everything to GBP takes hours per asset if done in a spreadsheet.
- Not registering for Self Assessment in time. If you were not already registered, you needed to notify HMRC by 5 October 2026 for the 2025-26 year. Missing the registration deadline creates a separate penalty issue with HMRC beyond the filing penalty.