Understanding Self Assessment and your tax return
Self Assessment tax return deadlines
You must send your Self Assessment tax return and pay any tax you owe to HM Revenue & Customs (HMRC) on time. There are a number of deadlines for Self Assessment that you must keep in mind.
The last tax year started on 6 April 2025 and ended on 5 April 2026.
Self Assessment deadlines
| Self Assessment type | Deadline |
|---|---|
| Register for Self Assessment if you need to complete a tax return and have not sent one before | 11:59pm on Monday 5 October 2026 |
| Paper tax returns | 11:59pm on Saturday 31 October 2026 |
| Online tax returns | 11:59pm on Sunday 31 January 2027 |
| Pay the tax you owe | 11:59pm on Sunday 31 January 2027 |
There is usually a second payment deadline of 31 July if you make advance payments towards your bill, known as payments on account.
If you fail to meet the deadline, you may have to pay a penalty. You can appeal against a penalty if you have a reasonable excuse.
When the deadline is different
Submit your online return by 30 December if you want HMRC to automatically collect tax you owe from your wages and pension. You must be eligible.
HMRC must receive a paper tax return by 31 January if you're a trustee of a registered pension scheme or a non-resident company. You can't send a return online.
HMRC might also email or write to you giving you a different deadline.
Partnership returns if you have a company as a partner
If your partnership’s accounting date is between 1 February and 5 April and one of your partners is a limited company, the deadline for:
- online returns is 12 months from the accounting date
- paper returns is 9 months from the accounting date
2024 to 2025 tax year and earlier
The Self Assessment deadline for these tax years has passed. Send your tax return or payment as soon as possible - you’ll have to pay a penalty.
