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If you're self-employed you must complete a Self Assessment tax return for any tax year during which you were self-employed. You need to complete a tax return even if you were only self-employed for part of the year. Before you complete your first tax return you'll need to register for business taxes with HM Revenue & Customs (HMRC). You can send your return online or on paper.
If you send your return online, you'll have three months longer to complete and send it.
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If you send your tax return online, you can tailor it and just complete the relevant sections. You get online help as you work through the form. Your tax will be worked out for you automatically and you get an acknowledgement when HMRC receives your return. You have longer to send in the return than if you send in a paper form. You have until 31 January after the end of the tax year instead of 31 October.
You need to sign up for HMRC Online Services before you can send your return online. You need to sign up whether you use commercial software or the HMRC Online service. If you're newly self-employed, you can do this automatically when you register for business taxes with HMRC. If you registered your business with HMRC before April 2012, you can follow the link below to sign up for HMRC Online Services.
Sign up for HMRC Online Services
Register for business taxes with HMRC]
Self Assessment Online - find out more
You usually receive a letter in April or May each year telling you to complete your tax return. If you want to send your tax return on paper, you can download the forms.
Make sure that you put your ten-digit tax reference number, called your Unique Taxpayer Reference (UTR) and your name and address on your tax return if you download it. You'll find your UTR on statements and letters from HMRC.
You use the main tax return form (SA100) to give basic details such as your name, address and straightforward investment income.
You will need supplementary pages to tell HMRC about your other income, for example:
Each supplementary page has a set of notes and to help you fill in the more complicated sections. There is further detailed guidance on relevant helpsheets.
Go to Self Assessment forms, guidance and supplementary pages
The self-employment pages you need depend on the amount of your turnover. You'll need:
You show details of your business income and expenses on the self-employment pages. These figures tell HMRC what your taxable profit is.
You will need different pages if your business is a partnership, follow the link below to find out more.
Partnership tax returns - find out more
Go to Self Assessment forms, guidance and supplementary pages
Before you can fill in your tax return you'll have to collect all the information you need. For the tax year (6 April to the following 5 April) you'll need:
You need to provide bank details if you want HMRC to repay any tax directly to your account. HMRC recommends this as it is quick and secure.
Record keeping for the self-employed - learn more
Tax allowances and reliefs for the self-employed - find out more
Tax rates and allowances - read the current rates
If you don't have exact figures you can use:
If you use a provisional figure, you must tell HMRC when you expect to have final figures.
Use the 'Additional Information' section to say how you arrived at these figures and why you can't use actual figures. If you make adjustments at a later date and you haven't paid enough tax, you may have to pay interest and penalties.
If you send your tax return late, you'll have to pay a penalty, so make sure you send it on time.
If you send in a paper tax return, it must reach HMRC by the later of midnight on 31 October after the end of the tax year the tax return covers or three months after the date of the letter telling you to complete a tax return.
You should send your return back in the envelope provided or send it to the Tax Office shown on the front page of the form. You won't get a receipt if you send a paper tax return.
If you've downloaded the form, it may not show a Tax Office address. You'll need to check your Self Assessment statement - or a letter from HMRC - to find the right address to send it to. Alternatively, you can follow the link below to find an address. Make sure that the form also shows your ten-digit Unique Taxpayer reference (UTR) and your name and address, before you send it.
If you miss the deadline for paper tax returns, you'll need to send your tax return online instead.
If you send your return online, it must reach HMRC by the later of midnight on 31 January or three months after the date of the letter telling you to complete a tax return. You'll get an acknowledgment that HMRC has received your return.
Read more about tax return deadlines and penalties
If you make a mistake on your tax return, HMRC may need to contact you before they can accept it. So if you're sending a paper tax return:
You can easily avoid making mistakes by sending your tax return online, but make sure you:
Do not send paid bills or receipts with your tax return.
Find out more about sending your tax return online
For information about accounting periods and what business expenses are allowable, download Helpsheet 222 How to calculate you taxable profits.
How to calculate your taxable profits (PDF 131KB)
For information about how to enter capital expenditure on your tax return, follow the link below.
If you need further help with filling in your tax return, you can ring the Self Assessment Helpline.
Contact the Self Assessment Helpline
You'll receive a tax calculation if you completed a paper tax return and asked for one. For online tax returns, you see the tax calculation earlier, before you send your return.
If you are due a repayment of tax, you'll usually get this automatically. But it may be set off against other tax instead if there is an amount due soon.
If you have tax to pay, it will either be collected through your tax code or you will have to pay it by 31 January. If it's collected though your tax code, you'll pay the amount back in equal instalments - usually over one year along with your normal tax deductions from your pay or pension. Check your Self Assessment statement to find out more.
Understanding your Self Assessment
statement
Tax return deadlines and penalties
Understanding and using Self Assessment Online
