Key takeaways
- The 2025/26 online tax return and any tax owed are due by 31 January 2027; paper returns were due by 31 October 2026.
- If you need to file for the first time, you must register by 5 October after the end of the tax year.
- Payments on account are due on 31 January and 31 July, each normally half of last year's bill.
- A late return costs £100 straight away, even if no tax is owed, with more penalties after 3, 6 and 12 months.
- Sole traders and landlords in Making Tax Digital also have quarterly update deadlines on 7 August, 7 November, 7 February and 7 May.
Self Assessment runs on a fixed calendar. Miss a date and penalties follow automatically, even if you owe no tax. This page lists the dates for the returns currently being prepared, the 2025/26 tax year, and the year after.
Key dates for the 2025/26 tax year
The 2025/26 tax year ran from 6 April 2025 to 5 April 2026.
| Date | Deadline |
|---|---|
| 31 July 2026 | Second payment on account for 2025/26 |
| 5 October 2026 | Register for Self Assessment if you need to file for 2025/26 and have not filed before |
| 31 October 2026 | Paper tax returns for 2025/26 |
| 30 December 2026 | File online if you want HMRC to collect tax under £3,000 through your 2027/28 tax code |
| 31 January 2027 | Online tax returns for 2025/26 |
| 31 January 2027 | Pay any balance of tax for 2025/26, and the first payment on account for 2026/27 |
| 31 July 2027 | Second payment on account for 2026/27 |
Key dates for the 2026/27 tax year
The 2026/27 tax year runs from 6 April 2026 to 5 April 2027.
| Date | Deadline |
|---|---|
| 31 January 2027 | First payment on account for 2026/27 |
| 31 July 2027 | Second payment on account for 2026/27 |
| 5 October 2027 | Register if you need to file for 2026/27 for the first time |
| 31 October 2027 | Paper tax returns for 2026/27 |
| 31 January 2028 | Online tax returns and balancing payment for 2026/27 |
Making Tax Digital quarterly deadlines
If you are a sole trader or landlord in Making Tax Digital for Income Tax, which started in April 2026 for qualifying income over £50,000, you also send quarterly updates through your software:
| Update period (2026/27) | Deadline |
|---|---|
| 6 April to 5 July 2026 | 7 August 2026 |
| 6 April to 5 October 2026 | 7 November 2026 |
| 6 April 2026 to 5 January 2027 | 7 February 2027 |
| 6 April 2026 to 5 April 2027 | 7 May 2027 |
The 2026/27 tax return is then submitted through the software by 31 January 2028. There are no penalties for late quarterly updates in 2026/27.
Penalties for missing a deadline
Late filing (if you are not in MTD)
| How late | Penalty |
|---|---|
| 1 day | £100 |
| 3 months | £10 a day for up to 90 days (maximum £900) |
| 6 months | 5% of the tax due or £300, whichever is more |
| 12 months | Another 5% or £300, whichever is more, or higher if information was deliberately withheld |
Late payment (if you are not in MTD)
| How late | Penalty |
|---|---|
| 30 days | 5% of the tax unpaid |
| 6 months | Another 5% of the tax unpaid at that date |
| 12 months | Another 5% of the tax unpaid at that date |
Interest is charged on late payments at the Bank of England base rate plus 4%. Penalties for MTD participants are points-based for late submissions and percentage-based for late payments; the points-based system is extended to all Self Assessment taxpayers from 6 April 2027. See HMRC penalties.
Registering for Self Assessment
If you need to file for the first time, for example because you started self-employment, began letting a property or had untaxed income, register by 5 October after the end of the tax year. HMRC then sends your Unique Taxpayer Reference (UTR). Registering late can lead to a failure to notify penalty if tax is unpaid at 31 January. See how to register for Self Assessment.
Payments on account
If your last Self Assessment bill was £1,000 or more and less than 80% of your tax was collected at source, you make two advance payments towards the next year’s bill, each half of the previous year’s liability, on 31 January and 31 July. See payments on account.
Other dates to know
- Amending a return: you can amend a return within 12 months of the 31 January filing deadline; the 2024/25 return can be amended until 31 January 2027. See amending a return.
- Capital Gains Tax on UK residential property: report and pay within 60 days of completion, separately from Self Assessment.
- Notices to file: if HMRC sends a notice to file after 31 October, you have three months from the date of the notice.
Frequently asked questions
When is the Self Assessment deadline for 2025/26?
31 January 2027 for online returns and payment. Paper returns were due by 31 October 2026.
What happens if I miss the 31 January deadline?
You get an automatic £100 penalty, and interest on any unpaid tax. Further penalties apply after three, six and twelve months, and late payment penalties apply from 30 days.
When do I need to register for Self Assessment?
By 5 October after the end of the tax year in which you first need to file, for example by 5 October 2026 for 2025/26.
When are payments on account due?
On 31 January during the tax year and 31 July after it ends.
Sources
Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance in October 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.