Self-assessment tips: How to complete your tax return in 2024

If HMRC requires you to submit a self-assessment tax return, the deadline for submitting an online form for the 2022/23 tax year is rapidly approaching on 31 January 2024.

Whether this is the first time you’ve submitted a self-assessment return or you’re an old hand at it, allowing yourself plenty of time to complete the online form could save you undue stress and expense.

If you file your return or pay your tax bill late, you could incur a penalty and you may also be charged interest on any payments that you make late.

Read on for top tips on how to get organised and submit your form accurately before the deadline.

1. Don’t forget to register for self-assessment

If you’ve never submitted a tax return online or you did not submit one for the last tax year, you’ll need to register for self-assessment with HMRC.

You can’t submit a tax return for the 2022/23 tax year (due by 31 January 2024) until you have received your Unique Taxpayer Reference (UTR) number, which can take between 10 and 21 days to arrive by post depending on whether you live in the UK or abroad.

The deadline for registering for self-assessment for the 2022/23 tax year was 5 October 2023. But if you’ve missed this, don’t panic.

You could minimise the risk of incurring a “failure to notify” penalty by registering as soon as you can, submitting your form before the 31 January 2024 deadline and paying any tax and National Insurance contributions due on time.

A financial planner could help you understand your situation and offer guidance on how to approach a late registration for self-assessment.

2. Allow yourself plenty of time to complete your tax return

The deadline for paper self-assessment returns passed on 31 October 2023. But you have until the end of January to submit your form online.

Filing your tax return may feel like a chore, but it’s worth planning in time to get yours done early. Leaving this important task until the last minute could cause you to rush, which may increase the potential for errors, not to mention stress.

How long it takes you to complete the form will depend on several factors including how organised your records are and how familiar you are with the process of submitting online.

If you’ve never used the online system, allow yourself time to learn how it works. You can complete the form in multiple sittings and save your progress each time. So, if you start working on your return well ahead of the deadline, this will allow you to locate missing information, seek help with any sections of the form you don’t understand and still submit before the deadline.

If you submit your return up to three months after the January deadline, you may be charged a late filing penalty of £100. The penalty is likely to increase the later you submit. You may also be charged interest on any late payments. So, it’s well worth allowing yourself plenty of time to submit your online tax return.

3. Have key information to hand before starting your return

While you can save your progress on the online form and return to it as many times as necessary, gathering the essential pieces of information required before you start could save you time and hassle.

The key pieces of information you will need includes:

  • Your 10-digit UTR number
  • Your National Insurance number
  • Details of your untaxed income (for example, self-employment income and dividends)
  • Records showing your taxed income (typically P45 and P60 forms)
  • Any contributions to charity or pensions that might be eligible for tax relief
  • Records of business expenses, such as receipts and invoices
  • Details of any benefits you have received.

4. Maintain accurate records throughout the year

It may be easier and quicker to complete your return if you have comprehensive and well-organised financial records to hand.

Try to get into good habits at the start of the tax year. For example, file all receipts and invoices, keep up to date with accounts by taking advantage of accounting software or employing an accountant, and conduct a monthly reconciliation to ensure that your financial records tally with your business bank balance.

HMRC may charge penalties if records are inaccurate, incomplete or unreadable and you must keep records for at least five years from 31 January following the relevant tax year.

5. Don’t forget to claim tax relief on “allowable expenses”

You could reduce your overall tax bill by claiming tax relief on “allowable expenses” when submitting your self-assessment tax return. These expenses include:

  • Charitable donations
  • Office supplies
  • Marketing costs
  • Business travel costs
  • Staff costs
  • Legal and financial costs
  • Work-related clothing costs
  • Unpaid invoices
  • Various costs related to working from home.

Further, the Autumn Statement, which was announced on 22 November 2023, made the “full expensing” tax break permanent. So, you could also deduct any spending on new machinery and equipment from your profits.

When completing your tax return online, you could calculate your expenses and deduct these from your gross income or select the “trading allowance” which will deduct £1,000 from your gross income.

There may also be tax allowances that you could benefit from. For example, you do not have to pay tax on any gains that fall under your Capital Gains Tax allowance, which was £12,300 for the 2022/23 tax year. However, you may still need to report these gains on your return.

A financial planner could help ensure that you’re making the most of any tax relief you’re entitled to while avoiding making false claims or failing to declare relevant income, both of which could result in penalties or even prosecution.

Personal tax planning could also help you complete the return more quickly and accurately while avoiding errors, leaving you to focus on your business and investments.

Get in touch

If you’re unsure about your tax liabilities or which tax allowances you could benefit from, we can help.

Please get in touch either by email at or by calling 0117 9303510.

Please note

This article is for information only. Please do not act based on anything you might read in this article. All contents are based on our understanding of HMRC legislation, which is subject to change.

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