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Mastering Your UK Self Assessment Tax Return

Published by Sanjay Gautam,
Posted Date: December 20, 2023 , Modified Date: April 18, 2024
Categories: Income Tax, Tax

If you are a UK taxpayer, you may need to file a tax return for the year ending 5 April 2023. You can file your tax return online or on paper, but online filing is faster, easier, and more secure.

Online Filing

Most people file their tax returns online, which has several advantages:

  • Convenient 24-hour service
  • Quick, easy, and secure process
  • Extra 3 months to file your tax return
  • Automatic calculation of your tax
  • Faster repayment if you are due one
  • Ability to save your details and finish later
Uk self assessment tax return online filing

To file online, you need to register for HMRC online services first, a process that may take up to 10 working days. Afterward, you can log in to your personal tax account and fill in your tax return online. Compatible software can also be used for online filing.

Paper Filing

If you prefer to file on paper, download and print the tax return form SA100 and any supplementary pages you need from [GOV.UK]. You can also order paper forms by calling HMRC on 0300 200 3610.

Sign and date the declaration on page TR 8 of your tax return and send it to the HMRC office address shown on the front of the form. Alternatively, you can authorise a tax adviser or a nominee to deal with your tax affairs on your behalf.

Deadlines and Penalties

The deadline for filing your tax return depends on whether you choose to do it online or on paper. The deadlines are:

  • 31 October 2023 for paper returns (or 3 months after the date of this notice if that is later)
  • 31 January 2024 for online returns (or 3 months after the date of this notice if that is later)

The deadline for paying any tax due, or any Class 2 National Insurance, is 31 January 2024.

If you miss the deadlines, you will have to pay penalties and interest. The penalties are:

  • A £100 penalty if your return is up to 3 months late
  • A £10 daily penalty for each additional day your return is late, up to a maximum of 90 days
  • A £300 or 5% of the tax due penalty, whichever is higher, if your return is more than 6 months late
  • Another £300 or 5% of the tax due penalty, whichever is higher, if your return is more than 12 months late
  • Interest and late payment penalties if you pay your tax late

You can appeal against a penalty if you have a reasonable excuse, such as a serious illness, bereavement, or fire. You can also ask HMRC to reduce a penalty if you have special circumstances, such as a disability, or if the penalty is disproportionate or unfair.

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Details in the Tax Return

The Self Assessment Tax Return form contains the following sections, and you need to fill in the section as per your applicability:

  • Your Personal Details: Provide your date of birth, name, address, phone number, and National Insurance number.
  • What makes up your Tax Return: Answer some questions to determine if you need to fill in any supplementary pages for different types of income, such as employment, self-employment, UK property, foreign, trusts, capital gains, residence, and additional information.
  • Income: Report your income from interest, dividends, pensions, annuities, state benefits, and other sources. Also, enter any tax taken off your income.
  • Tax Reliefs: Claim any tax reliefs you are entitled to, such as payments to registered pension schemes, charitable giving, blind person’s allowance, and marriage allowance.
  • Student Loan and Postgraduate Loan Repayments: Indicate if you have a student loan or a postgraduate loan and enter any repayments deducted by your employer.
  • High Income Child Benefit Charge: Enter the amount of child benefit you and your partner received and the number of children you claimed for if your income was over £50,000 and you or your partner got child benefit.
  • Incorrectly claimed Coronavirus Support Scheme Payments: Enter the amount of any payments you incorrectly claimed from any HMRC coronavirus support scheme, such as the Coronavirus Job Retention Scheme.
  • If you have not paid enough tax: Enter any tax refunded or set off by HMRC or Jobcentre Plus and indicate if you want any tax due to be collected through your wages or pension by adjusting your tax code.
  • If you have paid too much tax: Provide your bank or building society details or nominate someone else to receive your repayment and sign the authorisation box.
  • Signing your form and sending it back: Sign and date the declaration that the information you have given is correct and complete and send the form to HMRC by the deadlines. You can also provide your tax adviser’s details and any other information in this section."


Filing your UK tax return is a crucial responsibility that demands attention to detail and adherence to deadlines. The choice between online and paper filing offers flexibility, with online filing being faster and more convenient.

Penalties for late filing are clearly outlined, but avenues for appeal exist for those with reasonable excuses or special circumstances.

By staying informed about the various sections of the tax return form and meeting deadlines, taxpayers can navigate the process successfully, minimising the risk of penalties and ensuring compliance with HMRC regulations.

Seeking professional advice when needed and utilising HMRC resources contribute to a smooth and efficient tax filing experience.

Got questions about your UK Self Assessment Tax Return? 

Contact us today for efficient and hassle-free assistance.

Sanjay Gautam
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