Prepare your Self Assessment tax return - free, step by step
Quick answer
Answer a few guided questions and we'll prepare your full UK Self Assessment - Income Tax, National Insurance, student loan, Child Benefit charge and Capital Gains Tax all worked out, with a plain-English breakdown of what you owe and when. Free, region-aware for England, Scotland and Wales, and never submitted to HMRC on your behalf.
Use the Self Assessment Tax Return Wizard
About you and your income
Tell us where you live and how you earned money - we only ask about the sources you tick.
Which of these did you have in the tax year? (tick all that apply)
Your income for the year
Use your P60/P45, business records, dividend vouchers and bank statements. Whole-year totals, before tax.
Employment (PAYE)
Self-employment
UK property
Dividends
Savings interest
Capital gains
The first of gains is exempt. We apply in your basic-rate room and above it.
Expenses, allowances & reliefs
These reduce your bill - don't skip them. Not sure what you can claim? Run the expenses checker first.
Self-employment expenses
Best when your real expenses are under £1,000. You can't claim both.
Property expenses
Estimated bill so far
Total liability minus already collected at source. Calculated with 2026/27 rates.
This is an estimate and organiser, not tax advice, and nothing is sent to HMRC - confirm every figure on GOV.UK before you file.
- Total income
- Personal Allowance (tapered - income over £100k)
- Income Tax
- Class 4 National Insurance
- High Income Child Benefit Charge
- Student loan due via Self Assessment
- Capital Gains Tax
- Total liability
- Less PAYE / CIS already paid
Your profit is under the £ small profits threshold - you can pay voluntary Class 2 NI (£/week) to protect your State Pension record. Not added to this bill.
When you'd pay (31 January after the tax year ends, then 31 July)
- 31 January - balancing payment
- 31 January - 1st payment on account
- 31 July - 2nd payment on account
- Total due on 31 January
What goes where on your return
| Form / section | What to enter | Your figure |
|---|---|---|
Box numbers follow the current SA forms and can move slightly year to year - always match the description printed on the form or online screen you're completing.
Saved scenarios
| Scenario | Liability | Balance due | |
|---|---|---|---|
Source: GOV.UK official rates
What is Self Assessment?
Self Assessment is the system HMRC uses to collect Income Tax from people whose tax isn't taken automatically through PAYE. If you're self-employed, a landlord, an investor, a company director or a higher earner, HMRC expects you to declare your income each year and pay any tax due. This free wizard walks you through it section by section - like sitting with an accountant - and works out every figure for you.
Who needs to file a tax return?
You'll usually need to complete a 2025/26 Self Assessment return if any of these applied between 6 April 2025 and 5 April 2026: self-employment income above the £1,000 trading allowance; rental income above £1,000; dividends over £500; untaxed savings interest; capital gains above the £3,000 exempt amount; the High Income Child Benefit Charge; income over £150,000; or you're a company director with untaxed income. If you're not sure, our "Do I need to file?" checker gives you a quick answer first.
Key deadlines for the 2025/26 tax year
The 2025/26 return covers 6 April 2025 to 5 April 2026. Register for Self Assessment by 5 October 2026 if it's your first time (a Unique Taxpayer Reference can take about ten working days to arrive). File online and pay any tax by 31 January 2027. If your bill is large you'll also make payments on account towards next year - half on 31 January and half on 31 July. Missing the 31 January deadline triggers an automatic £100 penalty even if you owe nothing.
What you'll need before you start
Have your figures to hand: your P60 or P45 and any P11D for employment; your business income and expenses if you're self-employed; rental income and costs; dividend vouchers and bank interest; details of any assets you sold; pension contributions and Gift Aid donations; and any tax already paid through PAYE or CIS. You don't need an account to get your result, but a free login lets you save your answers and come back later.
How this wizard works
Tell us the tax year and where you live, tick the reasons you're filing, then choose how you earned income. We only ask about the sources you select, so freelancers, landlords and investors each see a tailored set of questions. At the end you get a full breakdown - Income Tax, National Insurance, the High Income Child Benefit Charge, student loan, Capital Gains Tax and your balance due - plus a plain-English explanation of what each number means and what to do next.
England, Scotland and Wales
The wizard is region-aware. Scottish taxpayers are taxed using the six Scottish bands (starter, basic, intermediate, higher, advanced and top), while England, Wales and Northern Ireland use the three UK rates. Savings and dividend income are always taxed at UK-wide rates. Select your region on the first step and the correct bands are applied automatically.
Making Tax Digital for Income Tax
From April 2026, sole traders and landlords whose combined gross self-employment and property income is over £50,000 must keep digital records and send quarterly updates to HMRC, then a final declaration by 31 January - the threshold falls to £30,000 in April 2027. This wizard helps you prepare and understand your figures; it does not replace MTD-compatible filing software where MTD applies to you.
Important
TaxFly prepares your figures so you can see exactly what you owe and how it's worked out. It does not submit anything to HMRC on your behalf. Every rate is based on published GOV.UK, Revenue Scotland and Welsh Government figures for the year you select, but always check against your own records before you file, and take professional advice for complex situations.
The dates and rules the wizard applies
| Deadline | What | Miss it and |
|---|---|---|
| 5 October 2026 | Register for Self Assessment (new filers, for 2025/26 income) | Penalties if the return is then late |
| 31 October 2026 | Paper return for 2025/26 | £100 automatic penalty |
| 31 January 2027 | Online return + payment for 2025/26 | £100 penalty, then daily fines from 3 months |
| 31 July 2027 | Second payment on account | Daily interest |
Full official guidance: GOV.UK Self Assessment. Never miss a date: free email reminders.
Reviewed by
Laura Michelle Davis - Chartered Tax Adviser (CTA)
ACCA · CTA (Chartered Tax Adviser) · ATT · BSc Economics, UC Berkeley
Laura Michelle Davis is a Chartered Tax Adviser (CTA) who also holds the ACCA and ATT qualifications and a BSc in Economics from UC Berkeley. She specialises in UK personal tax, covering income tax, National Insurance, self-employment and capital gains, and has built her career making complicated rules easy to follow. At TaxFly, Laura writes and edits the tax guides and explainers, checking that figures reflect current HMRC rates and that every explanation answers the question a real person is actually asking. Her goal is plain-English clarity you can trust and act on.
Frequently asked questions
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