How to complete your self-assessment tax return

20th December 2021
Written by Alice Hickling

Simplifying the online self-assessment tax return for freelancers, contractors, and the self-employed

Whilst completing a tax return may initiate feelings of dread or stress in many, tax returns are slowly getting more and more simple. Submitting a tax return online cuts out much of the leg work, leaving only the questions that are relevant to you.

If completing your annual tax return is something you want a little more guidance on, or if this year will be your first time completing a tax return, this guide will be particularly helpful to you.

Let’s first go through the basics before a guided walkthrough of the online self-assessment tax return process.

What is a self-assessment tax return?

A self-assessment tax return (SATR) is a method of calculating and paying tax owed on income. Self-assessment tax returns are an annual responsibility completed by 31st January for the previous tax year’s income. If you are new to self-employment, you will need to have registered for self-assessment by 5th October before being able to complete your SATR.

Who needs to complete a self-assessment tax return?

You need to complete a self-assessment tax return if any of the following apply to you within the previous tax year:

  • You earned over £1,000 as a self-employed sole trader
  • You were a partner of a business partnership

You will also need to complete a SATR if HMRC have sent you a notice to complete a tax return, even if you do not owe any tax.

If it isn’t clear whether or not you need to complete a tax return, take a look at the multiple-choice questionnaire here on the .gov website for a more definitive answer.

Before you get started

If this is your first time submitting a self-assessment tax return, you will first be required to register. For more information on registering for self-assessment see here.

Before you begin filling out your tax return, you will need the following information at hand.

  • Your ten-digit Unique Taxpayer Reference (UTR) (this can be found on HMRC correspondence from when you registered for self-assessment)
  • Your National Insurance number
  • Details of any untaxed income from the previous tax year
  • Record of any already taxed income (P60)
  • Record of relevant expenses
  • Record of any contributions to a pension or to charities


How to complete your online self-assessment tax return directly with HMRC

  • Sign into your Government Gateway account here and select the ‘Complete your tax return’ link under ‘Self Assessment’.
    Your Government Gateway account will have been set up during the registration process. This will require an access code sent to you either via text message or through a voice call.

  • Complete the ‘Tell us about you’ section which requests basic details such as your name, date of birth, taxpayer residency status, and more.
    Use the 'File a return' menu on the right-hand side to skip and return later. You may go through these step by step and can also save your progress to return to certain sections later.

  • ‘Tailor your return’ by answering these questions about your income and employment status. Your answers will dictate the following questions you will be asked throughout the rest of the assessment.
    From here we will just be focusing on the Self-Employed business section (SA103).

  • Next you will need to ‘Fill in your return’. You will need to complete information about your self-employed business, your income and expenses for the tax year (or accounting period) you are completing for, as well as any additional deductions such as Coronavirus income support.

  • Once all the relevant questions have been answered you will be invited to check your return. A red 'Error' message will display next to any sections you have not completed. Once your SATR is complete and you are happy that you have answered the questions correctly, you can press ‘Next’ to proceed.

  • You can then view your tax calculation detailing the total amount due for the previous tax year. It also provides a breakdown of the payments due and a more detailed version of your entire tax return is available by clicking the ‘View and print your full calculation’ option.

  • Finally, you can save a copy of your self-assessment tax return for your records and submit your return. You will be able to make payment online usually within 48 hours of submission so you will need to complete your return with sufficient time to pay if you wish to use this method.

How to complete your self-assessment tax return through GoSimpleTax

  • Completing a self-assessment tax return can be daunting. That’s why we provide every Qdos customer with 30% off the self-assessment tax return service with GoSimpleTax. This service is free to sign up and get started with. The premium version however includes added benefits such as direct filing with HMRC.

  • The tool automatically calculates the amount of tax owed and can be completed throughout the year, meaning you can keep track of income and expenses throughout the year and when January comes, all you need to do is submit to HMRC and pay your tax bill!

  • Another important element of the service provided by GoSimpleTax is that it highlights any mistakes made as well as if you are entitled to any savings.

  • As you are welcomed to GoSimpleTax, you will be asked to select any sources of income you receive such as self-employment, employment, pensions, and more. This will determine the sections of the SATR you need to complete.
    You can add sections at any time from your dashboard by selecting ‘New Page’. When completing your next year’s SATR, the system will automatically apply the same options unless you select otherwise.

  • From your dashboard, you will need to complete your ‘Personal Details’ via the button provided, as well as your business details via the ‘Edit’ button next to the title of the page you are viewing (Example: Self-employed (SA103).
    Here you will input details such as your name, date of birth, and unique tax reference, and details about your business necessary for submitting to HMRC.

  • You are now ready to add ‘Income’ and ‘Expenses’ which you can either at one time (much like with HMRC), or throughout the year.
    Using the handy mobile app, you can even do this on the go and add pictures of your receipts for your records. With GoSimpleTax you can record your income in real time, ensuring the countdown to the self-assessment tax return deadline is stress-free. Alternatively, integrate with your favourite bookkeeping tools including FreeAgent, FreshBooks, QuickBooks, SumUp, and Xero (beta) and leave the hard work to them. 

  • Once this is complete, with the premium version of GoSimpleTax’s tool, you can view a report which gives you details of the tax and NICs you will need to pay. Finish by clicking the ‘Validate your tax return’ button. Along the top is a section that keeps track of the progress of your tax return and the deadline for submitting.
    If submitting directly to HMRC through the GoSimpleTax tool, HMRC will confirm receipt of your self-assessment via email.

Alternatively, use our free tax calculator to find out how much tax you owe - no sign up required.

More information about Self-Assessment Tax Returns

For more information on self-assessment tax returns and which taxes are applicable to you, download our free Starter Guide to Tax for the Self Employed.

Please note that Qdos will receive a nominal referral fee from GoSimpleTax for registrations made via public links on the Qdos website, including those provided in this article. Qdos customers should sign up via links provided in customer accounts and/or in email communications to claim the 30% discount available with your policies (Qdos does not receive a commission for these discounted purchases).

Alice Hickling
Written by
Alice Hickling
Part of the Qdos marketing team, Alice Hickling is our chief Copywriter. She has worked in the contracting industry for over 4 years with bonus experience as an IR35 Status Consultant. She gets a kick out of the written word but is also responsible for singlehandedly keeping the plants of the Qdos office alive. A role she does not take lightly.

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