What is a Self-Assessment Tax Return Form


If you’re self-employed then you’ll probably want to familiarise yourself with some of the details of the self-assessment tax return form.

It’s a really important part of your business administration and any misunderstanding could result in hefty penalties.

I’ve put together this post to give you:

  • An overview of the form;
  • How and when you need to file it.
  • Where you find it;
  • The main sections that make it up;
  • What an example self-assessment tax return form looks like.

What is a Self-Assessment Tax Return Form

A self-assessment tax return is a form completed online by anyone who receives untaxed income.

Untaxed Income includes things like:

  • Rental income;
  • Self-employment earnings;
  • Dividends;
  • Bank interest;
  • Pensions.

It’s unlike when you are employed by someone and they handle your taxes for you, deducting tax from your wages before you get paid.

A tax return form is a summary of everything a person has earned during one complete tax year.

That means if you are employed and self-employed, for example, you would need to include your employment earnings on your tax return. An adjustment is made in your tax calculation for any tax that was deducted from your pay by your employer.

When Should You File Your Tax Return

One self-assessment tax return form covers one tax year and is due by 31 January following the end of that tax year.

A tax year runs from 6 April to 5 April.

So the tax return for 2018/2019 covers the year 6 April 2018 to 5 April 2019 and is due for filing by 31 January 2020.

In addition to filing your self-assessment tax return by 31 January you’ll need to pay any tax and national insurance due, along with a payment on account.

A payment on account is a contribution towards your following years tax bill and you can read more about it here.

Where to find your Self-Assessment Tax Return Form

The easiest way to do your tax return is to fill it in online.

You can also fill in a paper version but this needs to be completed and filed earlier. By the 31 October, instead of 31 January.

You can access your self-assessment tax return online in your Government Gateway account.

This is the account you would have set up when you registered as self-employed.

If you can’t find your user ID or password then you can check here to find out how you retrieve it.

What are the Main Sections of the Self-Assessment Tax Return Form

A self-assessment tax return form is made up of different sections – the main section and supplementary sections.

Each supplementary section covers a separate form of income or piece of information.

Self Assessment Tax Return Main Section

This section contains details of your personal information such as your:

  • Full name
  • Address
  • National insurance number
  • Date of birth

You’ll also need to use this form to let HMRC know whether you receive income from:

  • Employment;
  • Self-employment;
  • A partnership;
  • UK Property;
  • Foreign income;
  • A trust;
  • Capital Gains.

If you have received any of the above you’ll need to fill out additional pages of your tax return specifically designed for each.

Within the main section of the self-assessment tax return you’ll also need to declare your income from:

  • Pensions;
  • Annuity;
  • Interest;
  • Dividends.

Self Assessment Tax Return Supplementary Sections

The supplementary sections available are:

You only need to fill out and include the supplementary sections relevant to you. 

When it comes to filing your tax return online, you’ll only be shown the supplementary pages you need to complete. This is based on what you ticked in the main section.

Example Self-Assessment Tax Return

Here are two examples of the paper version of the self assessment tax return form.

Tax Return Example

Self-Employment Supplementary Page Example

The online version is the same, but is easier to navigate since HMRC splits the return down into bite-sized sections.

Can You Fill Out Your Own Tax Return

You can choose to use an accountant or fill out your own tax return. But there is no legal responsibility to get a professional to do it for you.

It is your responsibility to file your tax return on time otherwise you’ll face penalties.

Still unsure? Do You Really Need an Accountant if You’re Self-Employed?

Updated 9 April 2019

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