How to Fill In Your Tax Return Online

Getting ready to fill in your HMRC tax return online? Wondering what sections you need to fill in? Not sure how to claim income tax allowances and reliefs? Or, are you new to self-employment and need some guidance to help get you through? You’re in the right place!

In this step-by-step guide, you’ll find everything you need to know to fill in your tax return online so you can beat the 31 January** HMRC deadline! There’s no jargon, I promise! However, there’s quite a lot of information. So, you may want to bookmark this page as you read it. That way you can come back to it as you work through each stage of filing your tax return online.

Friendly Disclaimer: Whilst I am an accountant, I’m not your accountant. The information in this article is legally correct but it is for guidance and information purposes only. Everyone’s situation is different and unique so you’ll need to use your own best judgement when applying the advice that I give to your situation. If you are unsure or have a question be sure to contact a qualified professional because mistakes can result in penalties.

1. When is Your HMRC Tax Return Due?

If you’ve set up a business and need to file a tax return, then the deadline for is 31 January, following the end of the tax year. A tax year runs from 6 April to 5 April. That means your 2020/2021 self-assessment form return is due by 31 January 2022.

There are penalties for failing to file your tax return (or SA100 form) on time, that increases the longer you leave it. Even though you may be able to appeal against any penalties you receive if you have a reasonable excuse. HMRC isn’t very generous with what they consider reasonable and don’t consider a lack of understanding an excuse. Plus, don’t forget filing a late tax return can be one of the ways a tax inspection is triggered.

You can choose to complete a paper tax return instead of doing it online. However, the tax deadline for sending this to HMRC is the end of the October. You should also be aware, HMRC only accept paper returns in specific circumstances so chances are you’ll need to file your return online.

It’s also worth noting that if you are employed and self-employed, pay any tax you owe through your PAYE code if it is below the limit set by HMRC. You’ll need to file your tax return online by the 30th December and arrangements will be made to change the tax code used by your employer to deduct what you owe out of your salary. Your employer won’t be told why there is a change in your tax code; they will just deduct more income tax on your payslip.

2. How Early Can You Fill In Your Tax Return Online?

Your tax return will be available for you to complete pretty much once the tax year ends. That means you can send in your tax return anytime after this. You won’t actually need to pay any tax you owe until 31 January. This means you can get your return completed whenever you’re are ready. Doing this means it’s out of the way earlier. Alternatively, if you are owed a tax refund, then you should get your return in as soon as you can. This way, you can get your tax repayment sooner rather than later.

3. Where to Find Your Tax Return

Your tax return will appear online in your .GOV account automatically once you have registered as self-employed. You can log in via your personal tax account to find it. You’ll have set up this account when you registered as self-employed/ Here’s what to do if you’ve lost your user ID or password.

Where to Find Your Tax Return Online

4. What You Need Before You Get Started Completing Your Tax Return

Getting all the documents you need ready in advance will make completing your HMRC tax return quicker and easier. You’ll only need documents that are relevant to the tax year you are filing your return for. Here’s some of the information you may need:

  • Personal details including your UTR number, National Insurance number and bank details if you are expecting a tax refund;
  • Partners Information if you want to claim Marriage Allowance;
  • Employment Information;
  • P45 or P60 if you were employed either full-time or part-time during the year;
  • P11d if you were employed and received a taxable benefit like private medical insurance or a company car;
  • Dividend certificates;
  • Bank interest certificates, if you need to show them on your tax return;
  • Student loan statements;
  • Pension statements and pension contributions;
  • Self-employment income and expenses from your accounts;
  • Rental income and expenses including managing agents statements, details of allowable expenses and mortgage statements;
  • Previous years tax return and details of any tax losses;
  • Details of any other taxable income you’ve received.

5. How to Fill in Your Tax Return Online

When you’re ready, it’s time to start filling in your tax return online. A self assessment tax form has various different sections. You only need to fill in the ones relevant to you. As a result, you’ll only be shown the ones you need to fill in based on the information you provide in the tell about you and tailor your return section.

5.1 Tell Us About You

You’ll need to start completing your return by filling out the “Tell Us About You” section. This section is your chance to check HMRC have the right personal information about you and for you to make any corrections necessary. For example, like a change of address. It will be pre-populated if HMRC has any of the information about you on their system already, but it still pays to check that everything is correct.

Some boxes like a phone number and email address are optional so it is up to you whether you want to provide it. However, it can be useful to add them in case HMRC need to contact you. Make sure that you:

  • Check all your personal details;
  • Ensure you tick the box to say you are UK Resident;
  • Tick the box if you are entitled to blind person’s allowance;
  • Enter information if you are making student loan repayments, the type of plan you are on and whether you are employed or self-employed.

Once completed you’ll move onto the tailor your return section where you tell HMRC about your different earnings. You can also remove any sections of the tax return that are not relevant to you.

5.2 Tailor Your Return

This section of your tax return lets you tell HMRC what types of income you have received and the types of income tax reliefs you want to claim that help to reduce your tax bill. There are three pages:

  1. Sources of income you have received like self-employment, employment or rental income;
  2. Interest and dividends;
  3. Income tax reliefs and allowances you plan to claim like the marriage allowance.

On the first page you’ll need to confirm the following:

** If you were self-employed during the tax year and your business turnover (not profit) is less than £1,000 then you can decide whether you claim the HMRC £1,000 trading allowance. It’ll mean you don’t need to declare your income but you also can’t:

Page 2 contains a list of questions to tell HMRC about all the other types of income you received during the tax year including:

  • Interest for example from UK banks, building societies or unit trusts;
  • Dividends for example from UK companies or open-ended investment companies;
  • UK pensions, annuities or state benefits;
  • Child benefit and whether you earned more than £50,000 because you may need to pay the high-income tax charge;
  • Lump sums, share schemes and life insurance gains.

If you made income tax losses during the tax year then you can let HMRC know about them here. This is because you may be able to offset these against your other forms of income. For example, investors who make a loss on an EIS company may be able to offset it against their capital gains or income tax.

If you made contributions towards a personal pension or retirement annuity, then you’ll be able to get tax relief on a certain amount of the contributions you make, currently up to £40,000. You’ll receive tax relief at the highest rate of tax you pay as long as you have:

  • contributed to a registered pension scheme;
  • received taxable UK earnings, such as employment income or profits from self-employment, or
  • are a resident in the UK for some time during the tax year or sometime in the 5 preceding years and when you joined the pension scheme.

Finally, you’ll also be able to claim any other tax reliefs on things like:

  • community investment tax relief;
  • venture capital trust shares;
  • maintenance/alimony payments relief.

Once you have tailored your tax return online to your personal circumstances, it’s time to start inputting the numbers. You’ll see all the sections you need to complete and be able to check your progress:

5.3 Employment Section

If you were employed by someone, you’ll need to enter your income from your P45 or P60. You should also comple more than one employment section if you had more than one employer during the tax year. You can claim tax relief on expenses that you paid for, but were not reimbursed by your employer; for example, if you had to work from home. If you own a Limited Company and have added yourself on the payroll, then you’ll also need to include details of this employment here too.

You’ll find a separate guide here to help you to complete the employment section of your tax return.

5.4 Self-Employment Section

You’ll be presented with the self-employment section if you have become self-employed, are a sub-contractor under the CIS scheme or are a registered foster carer. The first thing you’ll need to do is calculate your business turnover (excluding any SEISS grant you received. You can find out how to show your grant here). If it is less than £85,000, then you’ll be able to complete the short-form self-employment section which requires less information. Next, you’ll need to have your business expenses ready and then decide what tax reliefs like capital allowances and tax loss reliefs you want to claim.

You’ll find a separate guide here to help you to complete the self-employment section of your tax return.


5.5 Self-Assessment for the High-Income Child Benefit Charge

If you or your partner earn between £50,000 and £60,000, including through self-employment, then you’ll need to pay back any child benefit you have received in the form of an income tax payment. You can choose to do this by electing to stop receiving child benefit payments or paying the high-income tax charge by filling out an HMRC tax return. This charge claws back child benefits paid at a rate of 1% for every £100 you earn over £50,000. That means once your income reaches £60,000, you will not receive any child benefit.

You’ll find a separate guide here to help you to fill in your tax return for the high-income child benefit charge.

6. Paying Your Tax Bill

You can pay your self-assessment tax bill online in a variety of ways, including by direct debit, bank transfer and debit card. If you want to pay by bank transfer, then you’ll find the bank details on the HMRC website, unless your want to pay your self-assessment bill through your PAYE code.

HMRC takes non-payment of tax seriously and has the power to make you bankrupt and add penalties that escalate. That said, they will work with you if you are struggling to pay your tax bill. First of all, you must file your tax return in January. If you don’t you’ll face penalties until you do which only increase your debt. Once you know how much tax you owe, contact HMRC ASAP to discuss the situation with them. You can do this online or by phone and it means you can agree on a suitable repayment plan. By sorting out a repayment plan, it means you’ll freeze penalties and interest thereby stopping the amount you owe HMRC from escalating.

If you are due a repayment after filing your tax return, then be aware that there are significant delays with HMRC making tax refunds due to additional security checks taking place as a result of the increase in fraud as part of the Coronavirus pandemic. They are increasingly sending out SURF 1 and SURF 2 Tax Letters as part of their checks to request additional information as well as completed R38 forms.

7. Filling in an HMRC Paper Tax Return

HMRC paper tax returns are due for filing by 31 October and you can get one by:

  • Downloading it online;
  • Calling HMRC on 0300 200 3310 and asking them to send you a return.

8. What Happens if You Miss the Self Assessment Filing Deadline

If you miss the HMRC self-assessment tax return deadline, HMRC will issue automatic penalties. You may be able to have these reversed if you have a reasonable excuse. These start at an immediate £100, rising the longer you leave it. Interest is also applied for any outstanding tax.

9. Getting a Tax Refund After Filing Your Self Assessment Tax Return Online

If you are due a tax refund, you’ll need to let HMRC know that you want a repayment and enter your bank details. Once you have completed this, it can take up to 4 weeks for HMRC to process your refund and send it back to you.

10. How to Contact HMRC for Help Filling In Your Tax Return Online

If you have a question for HMRC about registering or the self-assessment then contact HMRC on 0300 200 3310.



About Anita Forrest

Anita Forrest is a Chartered Accountant, spreadsheet geek and money nerd helping financial DIY-ers organise their money so they can hit their goals quicker.