What are the SA103F and SA103S forms?

The SA103 forms are supplementary tax return forms filling out details about your self-employment on your Self Assessment.


Which type of SA103 form do I need to fill out?

If you are self-employed and have relatively simple accounts and your turnover was below £85,000, you can fill out the SA103S form, the short version.


You should complete the full self-employment form (SA103F) if:

  •  your turnover was £85,000 or more (or would have been if you’d traded for a full year) 
  • you’ve changed your accounting date 
  • you’re claiming Overlap Relief 
  • your taxable self-employed period, or basis period, is not the same as your accounting period and the income for the basis period is more than £1,000 
  • you have adjustment income because you changed your accounting basis 
  • you were within the Managing Serious Defaulters (MSD) programme during the year 
  • you need to adjust any profits chargeable to Class 4 NICs 
  • you had, on 5 April 2019, an outstanding untaxed balance on a disguised remuneration loan arising from this self-employment, even if it ceased between 6 April 2018 and 5 April 2019, and have not entered into a full and final settlement with HMRC

How do I fill in the SA103 forms?

You can find the SA103S here, and the SA103F here. You may need to fill in a form for each business, even if you only have one set of accounts, or if you recently started or ceased in business or have changed your accounting date.

The HMRC also provides a detailed guideline for each line item on the forms. Guidelines can be found here:

How do I submit the SA103F AND SA103S?

You can submit both of these alongside your main tax return (SA100).

Do I need to use the SA103F OR SA103S if I file my tax return online?

No, you will only need to fill these out if you submit your tax return on paper.

We recommend filing online–it is much easier and the sections you need to fill out will automatically be supplied. You also get an extra three months to complete it. 

By using GoSimpleTax, you can make tax season easier.  Our user-friendly software will sort through the details you provide and show only the sections relevant to you, saving you time and hassle. Make tax season easy and start your free trial today!

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GoSimpleTax provides you with a clear step-by-step process which means your tax return will be submitted faultlessly and painlessly.

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GoSimpleTax is the quick and easy software solution to managing all of your Self-Assessment and accounting information.

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