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Self-Assessment Tax Returns in the UK for 2023/24 tax year

For anybody required to complete a UK Self Assessment Tax Return, this article details all you need to do to ensure you meet the deadline

Written on 6 April 2023

If you live in the UK and work on a self-employed basis, you will need to understand the basics on how Self-Assessment tax returns works to ensure you meet the deadline of 31st January 2023.

We have broken down some of the essential information, along with guidance on both what it requires and how to approach the process.

It is important to remember that this information should be taken only as a guide, to help you with understanding the steps of this process only and must not be taken as direct advice toward any decision making.

Speaking to a UK tax professional is essential to ensure you are taking the correct steps and precautions in regards to your UK tax obligations, to help avoid making any mistakes or costly errors.

What exactly is Self-Assessment?

Self-Assessment is essentially the way you can report your income to HM Revenue and Customs as someone that is self-employed and pay your taxes on that income.

Self-Assessment only typically applies to self-employed, as income tax is commonly deducted automatically via the employer before the employee receives their salary wage.

This tax return will enable HMRC to calculate how much tax you owe in the UK, or any rebates which are owed to you, from income you received during the tax year under review.

Who will need to file a self-assessment tax return?

Other than the self-employed, others may need to file a self-assessment. Some of these people could be:

  • Receiving income from abroad
  • Registered as a company director
  • Earning £100,000 a year (or more)
  • The highest earning family member (over £50,000) in a family actively claiming child benefit
  • Someone that has earned £2500 or more in untaxed income (e.g., property renting)
  • Someone that has either savings or investments of higher than £10,000 before tax

To pinpoint exactly who needs to file a self-assessment tax return, you can request an introduction to one of our partners who will be able to determine whether you need to complete a UK tax return.

How do I approach filing a self-assessment tax return?

Self-assessments can be done both online and by post.

Postal applications require you to obtain the form SA100. This is available on the GOV.UK website, along with another detailed form which helps explain how to file and complete your paper tax return by post.

Online applications for self-assessments first require you to register with the GOV.UK website.

It is important to note that this can take up to 20 days in total, meaning it is vital to leave yourself plenty of time before any deadlines.

Once you are registered, the GOV.UK website offers an HMRC Self-Assessment online service. This is free to use and will allow you to submit your self-assessment tax return.

Registering with GOV.UK can differ, depending on your circumstances are as an individual.

HMRC will need to establish some information such as whether you are earning over £100,000, a partner in a partnership, self-employed or registered as a sole trader.

What documentation will I require for my self-assessment?

Making sure you acquire the full and correct paperwork for your self-assessment is crucial. These can be, but are not limited to:

  • Documents detailing any self-employment income (receipts, bank statements etc)
  • Documents detailing all savings and investments demonstrating how much interest earned and all other dividends earnings via statements
  • Summary of all expenses and rental incomes
  • A P11D or P9D (showing any benefits and expenses)
  • A P45 (applicable if you have left a job within the current tax year)
  • A P60 from any current employer showing all income and tax paid for that year
  • A Unique Tax Reference number (UTR) (issued to you upon registering for self-assessment)
  • Details of any gifts or donations made to charity

Deadlines and penalties

There are certain deadlines for different areas when it comes to your self-assessment.

Registering for self-assessment if you are self-employed, a sole trader, not self-employed or registering a partner or partnership is 5th October 2023.

Postal tax returns deadline is by midnight 31st October 2023.

Tax returns completed via online at GOV.UK have a deadline of midnight on 31st January 2024.

This means that all tax payments due must also be made by midnight 31st January 2024.

Penalties will occur if the payment deadline is missed. These penalties can be appealed when a reasonable excuse is plausible.

Other penalties can be for missing the deadline to submit your self-assessment, which is typically a penalty of £100. This amount will also usually increase if it is more than three months late. This can be increased to £10 for every day up to a maximum penalty of £900.

How can I pay HMRC for my tax return?

HMRC are able to accept payments through methods such as bank transfer and debit card payment directly.

You may also want to pay via cheque, which would have to be posted directly to HMRC. HMRC can also supply you with ‘paying in slips’, which can be used within your bank to deposit to them directly.

If you cannot pay your tax bill all at once, you may also have the option to spread your payments over a period of time using a payment plan.


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