Do I need to do a Self Assessment tax return?

Self Assessment is how HMRC collects tax on income that is not taxed automatically. If you are only an employee and your employer takes tax off your pay through PAYE (Pay As You Earn), HMRC usually has what it needs. Once you have income outside PAYE, you may need to do a Self Assessment tax return.

For the 2025/26 tax year (6 April 2025 to 5 April 2026), you usually need to file if any of these apply to you:

• You were self-employed as a sole trader and your income from it was over £1,000 before expenses.
• You were a partner in a business partnership.
• You had untaxed income, such as rent from a property, that is not covered by an allowance.
• You are a company director, in some cases, for example if you take income that has not been taxed through PAYE.
• HMRC asked you to file. If you receive a notice to file a return, you must send one, even if you think you owe nothing.

Not every situation fits neatly into a list. If you are unsure, it is safer to check than to assume, because penalties for missing a return apply even when no tax is due.

You normally do not need a Self Assessment return if:

• All your income comes from a job or pension taxed through PAYE.
• Your self-employed income before expenses was £1,000 or less, covered by the trading allowance.
• Your rental income before expenses was £1,000 or less, covered by the property allowance.
• You let a furnished room in your own home and the rent is within the £7,500 Rent a Room limit.
• Your savings interest or dividends are covered by your allowances and HMRC has not asked you to file.

Many people now earn extra money alongside a job: freelance design, tutoring, delivery driving, crafts or reselling. The key test is the trading allowance, a £1,000 tax-free allowance for self-employed income.

• If your side income before expenses is £1,000 or less in a tax year, you do not need to register or report it.
• If it is over £1,000, you need to register for Self Assessment and file a return.
• When you file, you can either deduct your actual expenses or deduct the £1,000 allowance instead, whichever gives the better result. You cannot do both.

Note that the £1,000 is measured on income, not profit. If you sold £1,800 of handmade goods and spent £1,200 on materials, your profit is only £600, but your income is over £1,000, so you need to file.

Selling your own unwanted belongings, like old clothes or furniture, is generally not trading. Buying things to sell on for a profit usually is. If you sell online regularly, our page for online sellers explains what we look at.

Usually, yes. Rent is untaxed income, so if your rental income before expenses is over the £1,000 property allowance, you need to tell HMRC, normally through a Self Assessment return. If you use the property allowance, you cannot also deduct expenses, so it suits people with small rental income and few costs.

Our landlord tax return guide explains what to report and which expenses you can claim, and our property income allowance guide covers when the allowance is worth using.

You must register by 5 October after the end of the tax year in which you first need to file. A tax year runs from 6 April to 5 April. So if you started self-employment in, say, June 2025, that falls in the 2025/26 tax year, and the registration deadline was 5 October 2026. The return itself is then due online by 31 January 2027.

1. 1

   Work out which tax year you started

   Find the date your new income began and which 6 April to 5 April year it falls in.

2. 2

   Register with HMRC

   Register online on GOV.UK. There are separate routes for sole traders, for people who are not self-employed (such as landlords) and for partners, so choose the one that matches your situation.

3. 3

   Wait for your UTR

   HMRC posts you a Unique Taxpayer Reference, a 10-digit number. You need it to file, so keep it safe.

4. 4

   Keep records from day one

   Keep invoices, receipts and bank statements for the business or property. It makes the return much easier and supports what you claim.

5. 5

   File and pay by 31 January

   File your return online and pay any tax due by 31 January after the end of the tax year.

For a full list of dates, see our guide to the Self Assessment deadline.

It happens more often than people think. Someone starts a side business or lets a flat, does not realise they need a return, and a year or two goes by. The best thing to do is put it right yourself, before HMRC contacts you.

• Register now, even if the 5 October deadline has passed.
• Gather records for each year you should have reported, as far as you can.
• File the missing returns and pay the tax owed, plus any interest.
• If penalties arise and you had a genuine reason for the delay, you may be able to appeal.

HMRC generally treats people who come forward on their own more favourably than people it finds. Our late tax returns and penalty appeals service helps people catch up, and our guide to Self Assessment penalties and appeals explains how penalties work.

If you think you need to file for 2025/26, register straight away and start gathering your records. The online return and payment are due by 31 January 2027.

If you would rather someone checked whether you need a return and then handled it for you, our Self Assessment tax return service starts from £99 a month on a fixed fee. Get in touch for a free 20-minute chat and we will tell you where you stand.