If you still file your Self Assessment tax return on paper, time is running out. HMRC must receive your paper return for the 2025/26 tax year by 31 October 2026.
Miss that date and you face a late filing penalty. The good news: you can still file online instead. Here is what you need to know.
Who This Affects
The 31 October deadline applies to anyone who files a Self Assessment tax return on paper. It covers the tax year that ended on 5 April 2026.
Most people now file online. But some still use paper — often those who prefer it, or who started Self Assessment years ago and never switched. If that is you, 31 October is your hard deadline.
What Happens If You Miss It
File your paper return late and HMRC charges a £100 late filing penalty. This applies even if you owe no tax, or if you have already paid everything you owe.
Further penalties follow if the return stays outstanding. After three months, daily penalties of £10 per day can apply, up to £900. After six months, further penalties of £300 or 5% of the tax due kick in.
Do not try to fix a late paper return by filing online as well. HMRC is clear: filing an online return does not replace a paper return that was already submitted late.
Switch to Online Filing Instead
If 31 October looks tight, file online. The online deadline is 31 January 2027 — three extra months.
To file online you need a Government Gateway account and your Unique Taxpayer Reference (UTR). If you have never filed online before, register now. It can take a few days for HMRC to send your activation code by post, so do not leave it to the last minute.
Once registered, you can complete your return on HMRC’s website or through MTD-compatible software. Online filing also gives you an instant submission receipt, so you know HMRC has your return.
Key Dates to Remember
- 31 October 2026: deadline for paper Self Assessment returns (2025/26).
- 31 January 2027: deadline for online Self Assessment returns and for paying any tax you owe.
- 31 January 2027: deadline for your first payment on account for 2026/27, if you make payments on account.
Put these in your diary now. The January deadline also brings the payment deadline — filing and paying both land on the same day.
A Note for MTD Users
If you are already using Making Tax Digital for Income Tax, you send quarterly updates through your software during the year. Your year-end submission is separate. Keep your digital records up to date now and the January return becomes far simpler.
iFiler is HMRC-recognised software for MTD Income Tax quarterly updates. It keeps your income and expense records organised through the year, so your figures are ready when filing time comes. It is free for now.
Final Thought
Paper filers have four weeks left. If your return is ready, post it in good time — HMRC must receive it by 31 October, not just have it posted. If it is not ready, register for online filing today and give yourself until January.
Frequently Asked Questions
No. It applies to paper returns only. Online Self Assessment returns for 2025/26 are due by 31 January 2027.
HMRC must receive it by 31 October. Posting on the day is risky. Send it early, or switch to online filing.
Yes, file as soon as you can. But note that an online return does not cancel the late filing penalty on a late paper return. File now to stop further penalties building up.
You need a Government Gateway account and your Unique Taxpayer Reference. Register on GOV.UK. HMRC posts your activation code, which takes a few days to arrive.
No. Quarterly updates summarise your income and expenses during the year. You still complete a year-end submission to confirm your figures and work out your tax.
If you receive a tax bill by post rather than a filing request, our guide to Simple Assessment letters explains how to check it and avoid paying twice.
Disclaimer:
This guide provides general information about Self Assessment as of October 2026. Tax rules and HMRC guidance can change. Always consult with a qualified tax professional about your specific circumstances. That’s what we’re here for. In accordance with our normal practice this reference is given in good faith and in confidence, without legal liability on the part of the author or the company. The author assumes no responsibility or liability for any errors or omissions in the content of this site
The information provided in this blog is for general guidance and educational purposes only and does not constitute financial, tax, accounting or legal advice. iFiler, registered in England under Company Registration Number 15996173, has prepared this content to offer general insights into financial and taxation matters. Although every effort is made to ensure the accuracy and relevance of the information at the time of publication, no guarantee is given regarding completeness, accuracy or suitability for your specific circumstances.
Readers should not act, or refrain from acting, based solely on the information contained in this content. Professional advice tailored to your personal or business situation should always be obtained before taking any financial or tax related decision. iFiler accepts no liability for any loss or damage arising from reliance on the information presented in this blog.
