When is the self-assessment tax return deadline?
If you are self-employed, rent out a property or earn income from savings or investments, you may need to complete a self-assessment tax return. We run through the deadlines that have already passed – and the ones you still need to consider.
Sam Walker
Daily penalties are being given out to taxpayers who fail to submit their tax return on time, with late filers being fined £10 a day.
Every year, the final self-assessment tax return deadline is 31 January, with HMRC requiring all eligible taxpayers to complete a self-assessment by that date.
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All late filers are fined a flat £100 if they don’t complete their self-assessment in time but after three months, those who still haven’t done it are fined an extra £10 a day.
When is the self-assessment tax return deadline?
There were two main deadlines for filing a self-assessment tax return for the 2024/25 tax year, depending on whether you did it online or by post.
The online deadline was 31 January 2026, while for those who preferred to file a paper tax return, it was 31 October 2025.
The January deadline applies to filing your return, and paying any income tax due – regardless which format of tax return you choose.
Some taxpayers also need to make payments on account. We explain that in more detail below.
The first deadline passed on 31 January, but the second payment on account deadline is fast approaching on 31 July.
A rundown of all the deadlines for the 2024/25 tax year can be found below.
Date | Deadline |
|---|---|
5 October 2025 (Passed) | Registering for self-assessment |
31 October 2025 (Passed) | Filing a paper tax return |
30 December 2025 (Passed) | Filing an online tax return if you want HMRC to collect payments through PAYE |
31 January 2026 (Passed) | Filing your tax return online Paying your tax bill First payment on account |
31 July 2026 | Second payment on account |
What happens if I miss the self-assessment tax return deadline?
If you missed the self-assessment tax return deadline, you have to pay a penalty to HMRC. The size of this penalty depends on how late you are and why you filed your tax return late.
Failing to submit your self-assessment on time means you could face paying a penalty of hundreds, or even thousands, of pounds depending on length of delay.
You’d also have to pay, as it stands, 7.75% interest on top (the Bank of England base rate plus 4%).
One day late
There is a flat £100 fine for filing the return late, even if only by one day.
Three months late
After three months (so if you file an online tax return, that means from 1 May), you get hit with additional daily penalties of £10, up to a maximum of £900.
We are now in this period.
Six months late
After six months, a further penalty applies – either 5% of the tax due or £300, whichever is greater.
12 months late
The same fine (5% or £300) applies again once you are 12 months late.
Paying your tax bill late
You can also be hit with a penalty if you pay your tax bill late.
You get a penalty worth 5% if you have not paid your tax bill after 30 days.
This 5% penalty applies again at six months and 12 months. Interest is also charged on top.
Self-assessment is payable via gov.uk or you can download the HMRC app and pay that way.
Some people put off dealing with their paperwork because they can’t afford to pay their tax bill but this is a bad idea.
Anyone who may struggle to pay their bill in full can contact HMRC about a possible payment plan.
What happens if I make a mistake with my tax return?
If you make a mistake with your tax return, you can correct it even after the deadline. Mistakes can be corrected within 12 months of the return being filed, with a new tax bill due on the updated return.
You will need to wait at least 72 hours after filing your return to make any changes.
How do payments on account work?
Payments on account are advance payments you make towards your next tax bill ahead of the deadline.
They are designed to help you spread the cost of your tax rather than having to pay it in one go.
There are two payments on account due, each of which is around half of the previous year’s tax bill. Once you file your tax return, you can determine whether a top-up payment is needed in order to clear the amount owed, or whether you can claim a refund.
For the 2024/25 tax year, the first payment on account deadline was 31 January 2026, and the second is upcoming on 31 July 2026.
If your tax bill is likely to be lower than the previous tax year, you can apply to have your payments on account reduced.
You can do this by signing into your online account via gov.uk and selecting the option to ‘reduce payments on account’.
How to hit the tax return deadline on time and avoid overpaying
To avoid unnecessary stress involved with filing a self-assessment tax return correctly and on time, there are several steps you can take.
First and foremost, give yourself as much time as possible.
While the ship has sailed for the 2024/25 tax year, you can still prepare yourself well in advance for the upcoming 2025/26 deadline.
Because the postal service is still sending paper versions of the Unique Taxpayer Reference (UTR) number, the earlier you start, the better.
Gather together all the relevant paperwork before you start attempting to fill in the return – your payslips and P60, P45 or P11D forms, details of other income sources, savings and investments, pension contributions and charitable donations.
Understanding any applicable tax allowances and reliefs might help reduce the actual tax you have to pay.
Make sure you’re clear on any eligible expenses such as travel or uniform allowances. HMRC also allows up to £1,000 tax-free for casual income, like selling personal items or odd jobs.
Make sure everything is accurate before you submit – even errors made in good faith can incur penalty charges.
After you file for the relevant tax year, it’s worth planning ahead. Are there lessons you can apply to future years to reduce your tax bill?
Topping up your pension is a great way to lower your tax liability, as well as helping provide for your retirement.
Keep an eye on your tax code and check it remains accurate for your circumstances.
Who needs to file a self-assessment tax return?
If your only source of income is your salary and you are not self-employed, then you probably don’t need to file a tax return. Your income tax will be deducted from your salary before you receive it through PAYE (pay as you earn).
Pension income is generally taxed through PAYE too, if you exceed the personal allowance.
While many people associate self-assessment with the self-employed, it doesn’t just apply to that group.
If you earn income from savings and investments held outside an ISA, a business, second home or another source, it’s likely you will need to file a tax return.
In recent years, more people have been dragged into the self-assessment net due to fiscal drag – inflation has been high but tax thresholds have remained frozen, meaning the tax-free allowances are worth less than they once were in real terms.
If you’re unsure whether you need to file a tax return, HMRC’s online tool helps you check.
