Filing self-assessment tax returns is a responsibility that many individuals and business owners in the UK face every year. From freelancers and sole traders to landlords and company directors, the process requires careful attention to detail. While HMRC provides guidance, the reality is that many people make errors that result in penalties, delays, or unnecessary stress.
Understanding the most common mistakes can save you both time and money. Whether it’s missing deadlines, submitting incomplete information, or misunderstanding allowable expenses, these errors can quickly add up. Filing correctly not only keeps you compliant with HMRC but also gives you peace of mind knowing that your finances are in order.
For those who find the process overwhelming, turning to professional help can be a smart move. Reliable UK-based firms, such as Account Ease, specialize in simplifying tax obligations and guiding individuals through every step of the filing process.
This article highlights the most frequent mistakes people make when submitting their self-assessment and how you can avoid them to stay on the right track.
Missing the Filing Deadline
One of the most common mistakes is simply missing the deadline. HMRC sets strict submission dates for self-assessment tax returns, and late filing can lead to instant fines. Even if you have no tax to pay, penalties still apply when the return is late.
To avoid this:
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Mark key dates in your calendar well in advance.
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Consider submitting your return early to prevent last-minute issues.
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Use reminders and digital tools to stay on top of deadlines.
Submitting early also provides more time to correct any errors that might appear in your return.
Providing Inaccurate or Incomplete Information
Accuracy is crucial when filing self-assessment tax returns. Errors such as incorrect income figures, missing National Insurance numbers, or incomplete expense records can trigger HMRC enquiries or additional penalties.
Common issues include:
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Forgetting to include all income sources (such as rental income or side jobs).
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Entering incorrect tax reliefs or allowances.
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Mixing personal and business expenses.
Maintaining well-organized financial records throughout the year makes the process smoother. Working with a tax specialist can also ensure that your figures are correct and all details are covered.
Misunderstanding Allowable Expenses
Many self-employed individuals and landlords miss out on tax relief because they either overclaim or underclaim expenses. Both mistakes can be costly. Overclaiming may lead to HMRC penalties, while underclaiming means you’re paying more tax than necessary.
Allowable expenses can include:
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Office costs like phone bills or stationery
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Travel expenses for business purposes
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Costs of equipment, tools, or uniforms
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Certain home-working expenses
The rules can be complex, which is why guidance from professionals can prevent mistakes. This is where websites such as Account Ease prove valuable, offering insights into what can and cannot be claimed.
Forgetting to Report Additional Income
Another frequent oversight is forgetting to declare additional income. For example, dividends, rental income, or overseas earnings must be included in your return. HMRC has access to multiple data sources, so undeclared income is likely to be flagged.
To avoid issues:
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Keep detailed records of all earnings, not just your primary source of income.
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Double-check every section of the return before submission.
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Consult guidance if unsure about what needs to be reported.
Being transparent ensures compliance and helps you avoid fines or audits.
Ignoring Payment Deadlines
Filing the return is only part of the process. You also need to pay the tax owed by HMRC’s deadline. Late payments result in additional penalties and interest charges.
To prevent this mistake:
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Calculate how much you owe well before the deadline.
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Budget for your tax bill throughout the year to avoid cash flow issues.
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Set up reminders for both submission and payment deadlines.
Staying proactive about payments reduces financial stress and keeps you in good standing with HMRC.
Final Thoughts
Avoiding mistakes in self-assessment tax returns comes down to preparation, attention to detail, and understanding your obligations. From deadlines and expense claims to income reporting and payments, each step requires care.
For those who find the process challenging or time-consuming, professional support can make all the difference. UK-based firms like Account Ease provide tailored tax return services that ensure accuracy, compliance, and peace of mind.
By avoiding common mistakes and seeking expert help when needed, you can stay on top of your tax responsibilities and focus more on running your business or personal goals.
FAQs
1. Who needs to file a self-assessment tax return?
Anyone self-employed, a company director, earns rental income, or has untaxed income, may need to complete a return.
2. What happens if I miss the filing deadline?
You’ll face an automatic penalty, even if no tax is due. Additional penalties increase the longer you delay.
3. Can I correct mistakes after submitting my return?
Yes, HMRC allows amendments within a set time frame, but it’s always better to get it right the first time to avoid complications.
4. Do I need professional help to file my return?
Not always, but many individuals prefer using professional services to ensure accuracy and avoid costly errors. Websites like Account Ease can provide the guidance needed.
