When Does My Tax Return Need to Be Submitted? UK Deadlines for 2025/26 and 2026/27
Missing a Self Assessment deadline costs £100 automatically — even if you owe HMRC nothing at all. In 2024 alone, more than 1.1 million people missed the filing deadline, and HMRC collected roughly £325 million in penalties and interest from late self-assessment payments the following year.
If you’re asking “when does my tax return need to be submitted?”, the answer depends on how you file and your specific circumstances. This guide sets out every 2025/26 and 2026/27 deadline, the exact penalty structure, and how the new Making Tax Digital rules change things from April 2026.
Your Self Assessment tax return must reach HMRC by 31 October (paper) or 31 January (online) following the end of the tax year on 5 April. For the 2025/26 tax year, that means paper by 31 October 2026 and online by 31 January 2027. Payment of any tax owed is also due by 31 January, regardless of which method you used to file.
Why Trust This Guide?
Written and reviewed by Shamayun Chowdhury, CIMA-qualified Senior Accountant at Major Accountancy and Lecturer in Accounting at Nottingham Trent University, with 15+ years of UK practice experience. Every deadline and penalty figure in this guide is checked directly against GOV.UK’s official Self Assessment guidance. Last reviewed: August 2026.
Key Takeaways
- The main online tax return deadline is 31 January following the end of the tax year.
- Paper returns must be submitted earlier, by 31 October.
- Late filing triggers an automatic £100 HMRC penalty — even if no tax is owed.
- Payment is also due by 31 January; interest accrues on unpaid tax from 1 February.
- New self-employed workers and landlords must register with HMRC separately, by 5 October.
- From April 2026, Making Tax Digital for Income Tax applies to sole traders and landlords with qualifying income over £50,000, replacing the single annual return with quarterly digital updates.
- From April 2027, the MTD threshold drops to £30,000.
Table of Contents
- UK Tax Return Deadlines Explained: 2025/26 and 2026/27
- Special Rules for New Self Assessment Registrants
- What Is Self Assessment?
- What Happens If You Miss the Deadline?
- How to File Online and Avoid Late Fines
- Deadlines by Taxpayer Type
- Key Dates Calendar & MTD Changes
- Late Fines: What Counts as ‘Late’ and Appeals
- Help for Contractors, Landlords & Specific Sectors
- How Much Does an Accountant Cost?
- How to Find and Verify an Accountant
- Common Mistakes to Avoid
- FAQs
- Sources
- About the Author
UK Tax Return Deadlines Explained: 2025/26 and 2026/27
The UK’s tax year runs from 6 April to 5 April the following year. For the 2025/26 tax year, the paper deadline is 31 October 2026, and the online deadline is 31 January 2027. The same pattern repeats for 2026/27: paper by 31 October 2027, online by 31 January 2028. Payment is always due by 31 January after the tax year ends.
Every return covers income, gains and allowable expenses for the full 6 April to 5 April window — even if you only started trading partway through the year, your first return still covers this complete period.
| Deadline | What’s Due |
|---|---|
| 5 October | Register for Self Assessment if newly self-employed or receiving untaxed income |
| 31 October | Paper tax return deadline |
| 30 December | Online filing deadline if you want tax collected through your tax code |
| 31 January | Online tax return deadline and payment due date |
| 31 January & 31 July | Payments on Account (if applicable) |
Accountant Insight: Filing online by 30 December, rather than waiting until January, gives you the option of having a smaller tax bill collected gradually through your PAYE tax code the following year, instead of paying it as a lump sum on 31 January — worth considering if cash flow is tight.
Special Rules for New Self Assessment Registrants
If you’re new to Self Assessment, you must notify HMRC by 5 October following the end of the tax year in which you started trading or received untaxed income. Registering late doesn’t remove your obligation to pay by 31 January — it can instead set a different filing deadline (three months from the date of HMRC’s response), while the payment date generally stays fixed.
Accountant Insight: Many first-time filers register in good time but assume a later registration automatically pushes back their payment deadline too. It doesn’t — payment is still expected by 31 January, regardless of when you registered.
What Is Self Assessment?
Self Assessment is the system HMRC uses to collect Income Tax and National Insurance from people whose income isn’t taxed automatically at source — mainly the self-employed, landlords, company directors, and anyone with significant untaxed income such as dividends or savings interest. For a full breakdown of who must file, see our Self Assessment service page, or the official GOV.UK Self Assessment deadlines guidance.
What Happens If You Miss the UK Tax Return Deadline?
Missing a UK tax return deadline triggers automatic penalties and interest, regardless of whether you owe any tax.
| Late Period | Penalty |
|---|---|
| 1 day late | £100 fixed penalty |
| 3 months late | £10/day, up to £900 |
| 6 months late | 5% of tax due or £300, whichever is greater |
| 12 months late | A further 5% of tax due or £300, whichever is greater |
Interest is charged on unpaid tax from 1 February onward, separately from these filing penalties. A common misconception is that no tax owed means no penalty applies — the £100 fixed charge applies purely for filing late, regardless of your tax position.
Illustrative Example: A sole trader who files 4 months late with no tax owed still faces the £100 fixed penalty plus roughly £300 in accumulated daily penalties (£10 × approximately 30 days beyond the 3-month mark) — over £400 in charges, entirely avoidable by filing on time, even without paying the tax bill in full straight away.
Accountant Insight: Submitting your return on time — even if you can’t pay immediately — stops the filing penalties escalating. Interest still accrues on unpaid tax, but you avoid the £100-plus-daily-penalty stack entirely.
How to File Self Assessment Online and Avoid Late Fines
| Step | Action | Why It Matters |
|---|---|---|
| 1 | Register for an HMRC online account | Needed to access the portal and get your UTR |
| 2 | Gather income, expenses, UTR and NI number | Reduces errors and speeds up filing |
| 3 | Log in and enter your figures online | Gives instant confirmation of submission |
| 4 | Use MTD-compatible software if applicable | Required from April 2026 if your qualifying income is over £50,000 |
| 5 | Submit before 31 January | Avoids the £100 fine and daily penalties |
Register well before the deadline — HMRC can take up to 10 working days to issue your Unique Taxpayer Reference and activation code, longer if you register close to the deadline.
Accountant Insight: Starting to gather your figures in April, right after the tax year ends, rather than in January, is the single biggest factor separating a smooth filing from a rushed, error-prone one.
Tax Return Deadlines by Taxpayer Type
- Sole traders and freelancers: Online by 31 January, paper by 31 October, payment also by 31 January. Applies to anyone with untaxed self-employed income.
- Landlords: If rental income exceeds £1,000 a year, a return is required. Even if income is under this, a filing is still needed if HMRC has issued a notice to file.
- Limited companies: Must submit a Corporation Tax return (CT600) within 12 months of the financial year end, but payment is due sooner — 9 months and 1 day after year end. Companies House accounts are a separate deadline again, often confused with the Corporation Tax dates.
- Freelancers: Treated as sole traders for Self Assessment purposes, with the same 31 January/31 October deadlines — though additional employment or dividend income can add complexity.
Accountant Insight: Company directors frequently conflate their personal Self Assessment deadline with their company’s Corporation Tax and Companies House deadlines — these are three separate obligations with three separate dates.
Essential UK Tax Return Dates: Calendar & Making Tax Digital Changes
From April 2026, Making Tax Digital for Income Tax became mandatory for sole traders and landlords with qualifying income (gross, not profit) over £50,000, based on their 2024/25 tax return. The threshold drops to £30,000 from April 2027, based on the 2025/26 return.
This is a significant shift for those affected: rather than a single annual return, MTD requires digital record-keeping and quarterly updates submitted through MTD-compatible software, with a final year-end declaration replacing the old annual return process.
Payments on Account also catch many first-year filers off guard. If your tax bill is over £1,000 and less than 80% of your tax was collected at source, you’ll make advance payments toward next year’s bill on 31 January and 31 July — missing these triggers interest and penalties in the same way as a standard late payment.
Tax Return Fines: What Counts as ‘Late’ and How to Appeal
Late fines are triggered the moment a deadline passes, even if you owe nothing. Appeals are only successful where there’s a genuine, documented “reasonable excuse” — such as serious illness, bereavement, or an HMRC system failure — and even then, HMRC and tribunals apply this test strictly.
To avoid fines: submit early, keep digital reminders of your deadlines, and retain all HMRC correspondence in case a query or appeal is ever needed.
Accountant Insight: Even where you can’t pay your tax bill in full, always submit your return on time. Filing stops the escalating late-filing penalty stack; a separate Time to Pay arrangement can then be agreed with HMRC for the tax itself.
Self Assessment Help for Specific Sectors
Different sectors carry different filing nuances worth reviewing with a specialist:
- Contractors: IR35 status, allowable expenses, and multiple income streams.
- Landlords: Mortgage interest relief restrictions (Section 24), property repairs, and joint ownership reporting.
- Construction: CIS deductions, subcontractor statements, and refund eligibility.
- Healthcare professionals: Locum work, NHS pension reporting, and professional subscriptions.
- Taxi and private hire drivers: Mileage claims, vehicle costs, and cash income reporting.
Accountant Insight: It’s worth asking your accountant to review the last two tax years for missed allowances or errors — HMRC generally allows amendments within a set statutory window, and reviewing past returns often surfaces reliefs that were missed the first time round.
How Much Does an Accountant Cost?
Fees vary by complexity and taxpayer type. Here’s what to expect for 2025/26:
Simple Employee Return
£100–£250
Single untaxed income source alongside PAYE employment.
Self-Employed Sole Trader
£150–£500+
Turnover, expenses and allowable deductions reviewed and filed.
Landlord
£150–£600+
Rental income, mortgage interest relief and repairs reviewed per property.
Company Director
£200–£800+
Personal Self Assessment alongside dividend and salary reporting.
How to Find and Verify an Accountant
Whether you’re searching for support in Leicester, London, Birmingham, Manchester, Nottingham or elsewhere in the East Midlands, choosing between a local firm and a UK-wide online service affects your experience but not your compliance — the filing requirements are identical either way.
| Check | Why It Matters |
|---|---|
| ICAEW / ACCA / AAT registration | Confirms professional regulation |
| Practising certificate | Legal permission to practise |
| Professional indemnity insurance | Protects you if something goes wrong |
| Engagement letter | Sets out exactly what’s included in the fee |
| HMRC agent status | Allows them to deal with HMRC on your behalf |
Verify credentials directly through ICAEW’s Find a Chartered Accountant or the AAT Find an Accountant directory, rather than relying on claims alone.
Online vs Local Accountants
| Factor | Online | Local |
|---|---|---|
| Cost | Typically lower | Typically higher |
| Meetings | Virtual | Face-to-face available |
| Availability | More flexible | Office hours |
| Coverage | Nationwide | Limited to area |
Common Mistakes to Avoid
- Leaving registration until after 5 October. Can result in a shorter run-up to your filing deadline and possible late-registration penalties.
- Missing the 31 January online filing deadline. Triggers the £100 fixed fine immediately, then daily penalties from 3 months late.
- Assuming no tax due means no return needed. If HMRC has issued a notice to file, you must respond regardless of your tax position.
- Confusing Corporation Tax and Self Assessment deadlines. These are separate obligations for company directors, with separate dates.
- Filing without checking previous years for missed claims. Amendments are often possible within HMRC’s statutory window.
- Not accounting for the new MTD quarterly obligations if your income is over £50,000. The single annual return no longer applies once you’re within scope.
Frequently Asked Questions
When is my tax return due for 2025/26?
Online by 31 January 2027, or paper by 31 October 2026. Payment is also due by 31 January 2027.
Do I still get fined if I don’t owe any tax?
Yes. The £100 fixed penalty applies simply for filing late, regardless of whether any tax is actually due.
How much should I pay an accountant?
Fees typically range from £100 for a simple employee return to £800+ for company directors or more complex cases, depending on the number of income sources involved.
Can I switch accountants mid-year?
Yes. Your new accountant requests professional clearance from your previous one and takes over from there — settle any outstanding fees and authorise the new agent with HMRC.
Can an accountant deal with HMRC directly for me?
Yes, once you authorise them as your agent, they can file returns and respond to HMRC queries on your behalf.
What if I can’t pay my tax bill by 31 January?
Submit your return on time regardless — this avoids the filing penalties. You can then arrange a Time to Pay agreement with HMRC for the tax itself, though interest still accrues.
How does Making Tax Digital change my filing from April 2026?
If your qualifying income (self-employment plus property, gross) is over £50,000, you move from a single annual return to quarterly digital updates plus a year-end declaration, submitted through MTD-compatible software.
Sources & References
- GOV.UK — Self Assessment tax returns: deadlines
- GOV.UK — Self Assessment tax return penalties
- GOV.UK — Making Tax Digital for Income Tax
- ICAEW — Find a Chartered Accountant
- AAT — Find an Accountant
Conclusion
Knowing exactly when your tax return needs to be submitted — and what triggers a penalty — is the difference between a routine annual task and an avoidable fine. Whether you’re a sole trader, landlord, or company director, the safest approach is the same: register on time, file early, and pay by 31 January even if it means arranging payment terms afterward.
Need help meeting your deadline or checking whether MTD applies to you? Call 0116 4030595, email info@taxreturnaccountants.uk or get in touch for a free, no-obligation consultation.