How to complete the SA103 self-employment tax return form

The SA103 form is the document you need to complete so you can pay tax on income from self-employment.

There are two kinds of SA103:

• The short version, called SA103S, which can be used by most self-employed people
• The “full version”, called SA103F, which is used by sole traders with more complex situations (they earn over the VAT limit, are a practising barrister, use traditional accounting instead of the usual cash basis, etc.)

How do I know if I’m self-employed (sole trader)?

It’s not always as easy as it sounds. Self-employed is a broad term, often referring both to limited companies and sole traders. Here’s how to work out whether or not you’re a sole trader.

• Are you working with a full-time employment contract? Then you’re not a sole trader
• Are you using a limited company to do business? Then you’re an employee of your own company (or an umbrella company), but not a sole trader

Also, in case you’re wondering, the term “sole trader” is often used interchangeably with the term “self-employed”.

How do I fill it in?

You can get the “shorter” SA103S form from this HMRC page.

If you file a Self Assessment tax return every year, then HMRC might also send it to you.

In any case, make sure you first read the “Self-employment (notes)” pdf for that tax year – it’s on the same HMRC page.It explains what each line item on the form means, and how to fill it.

If you want the full version, download the SA103F form here instead.

How do I submit it?

You need to send it together with your SA100 form (the main tax return form) – you can’t file the SA103 by itself.

Can I send it to HMRC online?

No, you need to send it by post.

The good news is that you can choose to do your entire Self Assessment online. Plus you can get another 3 months to do it since the deadline for sending the paper form is October 31st, but for online tax returns is 3 months later (end of January).

At TaxScouts we can file your tax return online for you instead – and for a flat fee, regardless of how many sources of income you have.