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Self-assessment tax return

Self-employed tax return

By Ian Robinson

Article 2 of 10

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Self-employed tax return

If you are self-employed, you have to fill in a self-assessment tax return each year. 

Here, we review the options available to self-employed people when filling out their tax return and the processes they are likely to have to go through. 

And you can get a head start on your 2016-17 tax return with the Which? tax calculator. Tot up your tax bill, get tips on where to save and submit your return direct to HMRC with Which?. 

Self-employed tax return explained

If you need to fill in a self-assessment tax return, HMRC should notify you in April and ask you complete a paper tax return or make an online tax return.

In order to make an accurate tax return, you are expected to keep records, which you may need to produce if your tax return is queried. These should include details of all your sales and takings, and a record of your purchases and business expenses. You should keep your records for a minimum of six years.

Before you complete a tax return, you will need to register for self-assessment. You can do this online. Once you have registered, HMRC will issue you with a 10-digit Unique Taxpayer Reference (UTR) number.  

  • Use the Which? online tax calculator : our easy-to-use and jargon-free tax calculator offers personalised tax tips, and you can submit the form directly to HMRC.

Self-employed tax return – paper returns

If you want to send a paper tax return, you need to complete the main return (SA 100) and also some supplementary pages. Supplementary pages are for declaring details of your:

  • income from self-employment (SA 103S or SA 103F)
  • employment income (SA 102)
  • income from UK property (SA 105)  
  • other income and gains.

The supplementary pages you need depend on your business turnover. If it's below £73,000, use SA 103S; if it's above £73,000, use SA 103F. HMRC helpsheets are provided for supplementary pages.

The deadline to submit a paper self-assessment tax return for 2016-17 is 31 October 2017.   

Self-employed tax return – online returns

If you submit an online tax return, you can select the pages you need as you complete it. To make an online tax return, you need to register in advance and receive an activation code (Pin) through the post. 

Sole traders and most other self-employed people can submit a self-assessment tax return online without any problem, but a Partnership Tax Return (SA 800) can only be sent online in conjunction with specially developed commercial software.

The deadline to submit an online self-assessment tax return for 2016-17 is 31 January 2018.

Find out more: If you need more help with tax, or any other aspect of your finances, sign up to a £1 trial with Which? and you can speak to a member of our Money Helpline team to get individual guidance.

  • Last updated: April 2017
  • Updated by: Gareth Shaw
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