The UK tax year runs from 6 April to 5 April. The 2025 to 2026 tax year began on 6 April 2025 and ended on 5 April 2026, so its Self Assessment return is the one due now. The 2026 to 2027 tax year runs until 5 April 2027.
The Self Assessment deadlines
| What | 2025 to 2026 | 2026 to 2027 |
|---|---|---|
| Register for Self Assessment, if you have not sent a return before | 5 October 2026 | 5 October 2027 |
| Paper tax return | 31 October 2026 | 31 October 2027 |
| Online return, to have tax collected through your tax code | 30 December 2026 | 30 December 2027 |
| Online tax return | 31 January 2027 | 31 January 2028 |
| Pay the tax you owe | 31 January 2027 | 31 January 2028 |
Each deadline is 11:59pm on the day. If you register late, HMRC gives you 3 months from the date on its letter or email to send the return, but the tax is still due by 31 January 2027 for 2025 to 2026.
Payments on account
Once you are in Self Assessment, HMRC may ask for two payments on account towards the next bill, each due by midnight on 31 January and 31 July. For 2025 to 2026 they were due on 31 January 2026 and 31 July 2026, with anything left over due on 31 January 2027.
You do not need to make them if the tax you owed last year was less than £1,000, or if last year you paid more than 80% of the tax you owed outside Self Assessment, for example through your tax code.
Making Tax Digital: quarterly updates
From 6 April 2026, sole traders and landlords with qualifying income over £50,000 also send HMRC a quarterly update. Each covers the tax year so far:
| Period | Deadline |
|---|---|
| 6 April to 5 July | 7 August |
| 6 April to 5 October | 7 November |
| 6 April to 5 January | 7 February |
| 6 April to 5 April | 7 May, in the following tax year |
Our guide to Making Tax Digital for Income Tax says who it applies to, and from when.
Staying ahead of the dates
The deadlines are easiest when your records are up to date all year. Keep each expense and its receipt as it happens, and a doc for the tax year adds it all up the moment you need it.