Summary
The deadline for submitting your 2025/26 self-assessment tax return online is 31 January 2027. Miss it and you face automatic penalties — even if you owe no tax.
Who Needs to File?
You must file a self-assessment return if, in the 2025/26 tax year (6 April 2025 – 5 April 2026), any of the following apply:
- →You were self-employed with income over £1,000
- →You received rental income from property
- →You earned over £100,000 from employment
- →You received dividends from a company you own
- →You had untaxed income from savings or investments
- →You received Child Benefit and either you or your partner earned over £60,000
- →You were a company director
- →You had income from abroad
- →You made capital gains from selling assets (property, shares, etc.)
If you're unsure whether you need to file, get in touch and we'll advise you.
Key Deadlines for 2025/26
| Deadline | What it covers |
|---|---|
| 5 October 2026 | Register for self assessment if new to it |
| 31 October 2026 | Paper return deadline |
| 31 January 2027 | Online return deadline + any tax owed |
| 31 January 2027 | First payment on account for 2026/27 |
| 31 July 2027 | Second payment on account for 2026/27 |
What Happens If You Miss the Deadline?
HMRC issues automatic penalties regardless of whether you owe tax:
Interest is also charged on any unpaid tax.
What You'll Need to Prepare
Gathering these documents in advance makes the process straightforward:
Income
- ›P60 or P45 (if also employed)
- ›Self-employment income records / invoices
- ›Rental income statements
- ›Bank and savings interest statements
- ›Dividend vouchers
Expenses (self-employed)
- ›Office / home office costs
- ›Travel and vehicle expenses
- ›Professional subscriptions
- ›Equipment and software
- ›Accountancy fees
Other
- ›Pension contributions
- ›Gift Aid donations
- ›Details of any capital disposals
How We Handle It
Filing your own self-assessment return carries risks — miscalculations, missed reliefs, and errors can trigger HMRC enquiries or result in overpaying. Our team handles the entire process:
Initial consultation
We assess your situation and confirm what needs filing.
Document collection
We provide a simple checklist of what to gather.
Preparation
We calculate your tax liability, claiming all allowable reliefs.
Review
You check and approve before anything is submitted.
Submission
We file directly with HMRC on your behalf.
We also advise on payments on account, reducing your tax bill legally, and planning ahead for next year.