Worried about the Self Assessment tax return deadline for the 2025/26 tax year, filing it before the deadline is important. Missing a filing or payment deadline can result in penalties and interest.
For most people filing online, the main self assessment tax return deadline is 11:59 pm on 31 January 2027. This is the deadline for submitting an online return for the tax year that ran from 6 April 2025 to 5 April 2026.
However, 31 January is not the only date that may matter. The correct deadline can depend on how you file, whether you need to register for Self Assessment and whether you want tax owed to be collected through your PAYE tax code.
This guide explains the key Self Assessment deadlines for 2027 and what you need to know.
What Is the Self Assessment Tax Return Deadline for 2027?
For the 2025/26 tax year, the Self Assessment tax return deadline is:
31 January 2027 at 11:59 pm
This is also normally the deadline for paying any Self Assessment tax owed for the 2025/26 tax year.
The 2025/26 tax year started on 6 April 2025 and ended on 5 April 2026.
You can submit your online tax return from 6 April 2026, so there is no need to wait until January 2027 to file.
Key UK Self Assessment Deadlines for 2027
Here are the main dates to keep in mind for the 2025/26 tax year.
5 October 2026: Tell HMRC You Need to Complete a Tax Return
This deadline does not apply to everyone.
You must tell HMRC by 5 October 2026 if you need to complete a tax return for the previous tax year and either:
- You have not sent a tax return before, or
- You were registered previously but did not need to send a return for the 2024/25 tax year.
Depending on your circumstances, you may need to register or reactivate your Self Assessment account.
31 October 2026: Paper Tax Return Deadline
HMRC must normally receive a paper Self Assessment tax return by 11:59 pm on 31 October 2026.
If you miss this deadline, you may still be able to submit your return online. The normal online filing deadline is later, on 31 January 2027.
There are some exceptions, including situations where HMRC issues a tax return late and provides a different filing deadline.
30 December 2026: PAYE Tax Code Deadline
If you are eligible and want HMRC to collect tax you owe through your PAYE tax code, you normally need to submit your online tax return by11:59 pmm on 30 December 2026.
This option is only available to eligible taxpayers and depends on HMRC’s conditions.
31 January 2027: Main Online Filing and Payment Deadline
For most taxpayers filing online, this is the most important date.
By 11:59 pm on 31 January 2027, you normally need to:
- Submit your online Self Assessment tax return, and
- Pay the tax you owe for the 2025/26 tax year.
If you are required to make payments on account, your first payment on account for the following tax year may also be due on this date.
The amount due will depend on your individual tax position.
31 July 2027: Second Payment on Account
Some taxpayers are required to make payments on account towards their next Self Assessment tax bill.
Where payments on account apply, the second payment is normally due by 31 July 2027.
Payments on account are generally made in two instalments, with one due on 31 January and the second due on 31 July.
They are not required for everyone. For example, HMRC states that you normally do not have to make payments on account if your previous year’s tax bill was less than £1,000 or if you paid more than 80% of your tax outside Self Assessment.
When Can You Submit Your 2025/26 Tax Return?
You can submit your 2025/26 Self Assessment tax return from 6 April 2026.
Submitting early does not mean you have to pay earlier. Your normal payment deadline remains 31 January 2027.
Filing early can help you find out how much tax you owe and give you more time to plan for the payment.
Who May Need to Complete a Self Assessment Tax Return?
Not everyone in the UK needs to submit a Self Assessment tax return.
You must complete one if HMRC asks you to do so. Other people may need to submit a return because of their income or circumstances.
For example, Self Assessment may be relevant to people who receive income from self-employment, property or other sources that need to be reported.
Whether you need to file depends on your individual circumstances, and HMRC provides guidance to help people check whether they need to send a tax return.
What Happens If You Miss the 31 January 2027 Deadline?
If you miss the filing deadline, HMRC may charge a late filing penalty.
If you pay tax late, you may also have to pay interest and penalties.
The consequences depend on the circumstances and how long the return or payment remains outstanding.
It is usually better to submit the return on time, even if you cannot pay the full amount immediately, rather than delay filing because you cannot pay everything by the deadline.
HMRC may allow eligible taxpayers to set up a payment plan, depending on their circumstances.
What If HMRC Gives You a Different Filing Deadline?
The standard deadlines do not apply in the same way in every situation.
For example, if HMRC issues a notice requiring a tax return after the normal period, the filing deadline may be different.
HMRC’s current guidance states that where a person registers after 5 October 2026, HMRC will send them a letter or email with a different deadline for submitting the return. This will be three months from the date on the letter or email.
However, the payment deadline can still be 31 January 2027.
Always check the deadline shown in HMRC’s correspondence and your Self Assessment account.
How Do Payments on Account Work?
Payments on account are advance payments towards your next Self Assessment tax bill.
If you are required to make them, there are usually two payments:
- The first payment on account is due on 31 January.
- The second payment on account is due on 31 July.
Each payment is usually half of the previous year’s relevant tax amount.
If the payments on account do not cover your final bill, you may need to make a balancing payment. This is normally due by 31 January following the end of the relevant tax year.
If your income falls and you expect to owe less tax, you may be able to apply to reduce your payments on account. However, interest may be charged if they are reduced too much.
How to Avoid Missing the Self Assessment Tax Return Deadline?
Leaving your return until the final days of January can create unnecessary pressure.
A practical approach is to:
- Check whether you need to file a return.
- Tell HMRC or register where required.
- Gather your records and supporting information.
- Keep track of the relevant filing deadline.
- Complete and submit the return as early as possible.
- Check how much tax you need to pay.
- Plan for any payment due on 31 January.
- Check whether payments on account apply to you.
If your tax affairs are more complex, getting professional help early may give you more time to deal with missing information or tax queries before the deadline.
Frequently Asked Questions
What is the online Self Assessment tax return deadline for 2027?
For the 2025/26 tax year, the normal deadline for submitting an online return is 11:59 pm on 31 January 2027.
What is the paper Self Assessment deadline for 2027?
The normal deadline for a paper tax return for the 2025/26 tax year is11:59 pmm on 31 October 2026.
Do I have to pay my tax by 31 January 2027?
For most Self Assessment taxpayers, tax owed for the 2025/26 tax year is due by 31 January 2027. If payments on account apply, the first payment towards the next tax bill may also be due on the same date.
Your exact amount due depends on your individual circumstances.
What happens if I register late for Self Assessment?
If you need to tell HMRC that you need to complete a tax return and do so after 5 October 2026, HMRC’s current guidance says it will send you a letter or email with a filing deadline that is three months from the date of that correspondence.
You should check the specific deadline HMRC gives you. You may also face a penalty for failing to notify HMRC on time.
Can I file my Self Assessment tax return early?
Yes. For the 2025/26 tax year, you can submit your return from 6 April 2026.
Filing early can help you understand your tax bill and plan for the payment deadline.
Final Thoughts
The main self assessment tax return deadline for online returns is 31 January 2027 at 11:59pm, but other dates may apply depending on how you file and your circumstances.
For the 2025/26 tax year, the main dates are:
- 5 October 2026: Tell HMRC you need to complete a return in the circumstances set out by HMRC
- 31 October 2026: Normal paper filing deadline
- 30 December 2026: Deadline for eligible taxpayers who want tax collected through their PAYE tax code
- 31 January 2027: Normal online filing deadline and tax payment deadline
- 31 July 2027: Second payment on account where applicable
Checking the relevant deadlines early can help you avoid last-minute pressure and give you more time to prepare your return correctly.
If you need help understanding your Self Assessment obligations or preparing your tax return, Account Ease can provide professional accounting and tax support based on your individual circumstances.
