Self Assessment deadlines for the 2025/26 tax return
For the 2025/26 tax year (6th April 2025 to 5th April 2026) your online tax return and any tax you owe are due by 31st January 2027. Paper returns were due by 31st October 2026. If you're filing for the first time you needed to register by 5th October 2026, so register now if you haven't.
The key dates at a glance
| Date | What's due |
|---|---|
| 5th October 2026 | Register for Self Assessment if you need to file for 2025/26 for the first time |
| 31st October 2026 | Paper tax return deadline for 2025/26 |
| 30th December 2026 | File online by this date if you want tax under £3,000 collected through your PAYE tax code |
| 31st January 2027 | Online return deadline for 2025/26. Pay the balance for 2025/26 and your first payment on account for 2026/27 |
| 31st July 2027 | Second payment on account for 2026/27 |
What happens if I miss the 31st January deadline?
The penalties for a late Self Assessment return stack up quickly:
- £100 straight away, even if you owe no tax.
- After 3 months, £10 a day for up to 90 days (up to £900).
- After 6 months, a further 5% of the tax due or £300, whichever is higher.
- After 12 months, another 5% or £300, whichever is higher.
Paying late adds separate late payment penalties and interest on top. If you've a reasonable excuse, such as a serious illness, you can appeal.
What are payments on account?
If your last Self Assessment bill was £1,000 or more, HMRC usually asks for advance payments towards next year's bill. Each one is half of last year's bill, paid on 31st January and 31st July. You don't make them if more than 80% of your tax was already deducted at source, for example through PAYE. An accountant can apply to reduce them if your income has dropped.
I'm in Making Tax Digital. Do my dates change?
Yes. If your qualifying income from self-employment and property was over £50,000 in 2024/25, you joined Making Tax Digital for Income Tax from 6th April 2026. You'll send quarterly updates through compatible software, then a final declaration for 2026/27 by 31st January 2028. Your 2025/26 return is still filed the normal way by 31st January 2027. Read our Making Tax Digital guide for the full picture.
Is it too late to get an accountant?
No. Most firms take on Self Assessment clients right up to January, although the best ones fill up from November. If you want help, the earlier you ask, the more choice you have and the calmer the fee conversation is.
Frequently asked questions
When is the Self Assessment deadline for 2025/26?
The online deadline is 31st January 2027. That's also when you pay any tax owed for 2025/26 and your first payment on account for 2026/27.
What is the penalty for filing my tax return late?
£100 immediately, then £10 a day after 3 months for up to 90 days, then 5% of the tax due or £300 (whichever is higher) at 6 months and again at 12 months.
Can I still file a paper tax return?
Yes, but the paper deadline for 2025/26 was 31st October 2026. After that you need to file online.
Do I need to register before filing?
Yes, if it's your first return. HMRC needs time to send your Unique Taxpayer Reference, so register as soon as you can.
This guide is general information for UK taxpayers and was correct when last reviewed. Tax rules change, so check your own position with a qualified adviser.
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