How to Amend Self Assessment Tax Return?

How to Amend Self Assessment Tax Return

Filing your self-assessment tax return accurately is crucial, but what if you make mistakes? Don’t worry; the process to correct errors is simpler than you might think. Whether it’s a missed income or a deduction you forgot to claim, here’s a step-by-step guide to amending your tax return.

Table of Contents

What Self-Assessment Tax Return Amend?

Amending your tax return means correcting errors or providing additional information after you’ve already filed. It’s essential to rectify mistakes promptly to avoid potential penalties or interest charges.

When you submit your tax return, HM Revenue and Customs (HMRC) will assess it and issue a tax calculation based on the information provided. However, if you later realize you made a mistake or need to update your return, you can file an amendment.

Assessing the Error

The first step is to identify the mistake. Did you miss reporting income, claim an incorrect deduction, or input inaccurate figures? Review your original tax return and any supporting documents to pinpoint the error.

Check your bank statements, invoices, and receipts to ensure you have a complete picture of your finances. Sometimes errors can occur due to simple oversights, so take your time to review each section of your tax return carefully.

How to Amend

Using Online Platforms

Many online tax software platforms, such as FreeAgent, offer a straightforward process for amending your return. Log in to your account, locate the option to amend your return, and follow the prompts to make the necessary changes.

These platforms often guide you through each section of your tax return, making it easy to identify and correct errors. You’ll typically have the option to review your original submission alongside the changes you’re making, ensuring accuracy.

Through HMRC

If you filed your tax return directly with HM Revenue and Customs (HMRC), you can amend it using their online services. Alternatively, you can submit an amended return by post. Be sure to include your Unique Taxpayer Reference (UTR) and details of the amendments you’re making.

HMRC’s online portal provides a secure and convenient way to amend your tax return. You can access your account at any time and track the progress of your amendment.

Time Limit

You have until the 31st of January following the end of the tax year to amend your tax return. For example, for the tax year ending 5th April 2023, you must make any amendments by 31st January 2024.

It’s essential to adhere to this deadline to avoid potential penalties or interest charges. If you’re unsure whether you need to make amendments, it’s better to review your tax return sooner rather than later.

What You Can Amend

You can make amendments to various aspects of your tax return, including:

  • Income: Add any sources of income you initially omitted, such as freelance earnings or rental income. Ensure you have documentation to support the additional income.
  • Deductions: Claim deductions you overlooked, such as business expenses or charitable donations. Review your expenses thoroughly to identify any missed deductions.
  • Personal Details: Update personal information like your address or contact details. It’s crucial to keep HMRC informed of any changes to ensure you receive important correspondence.

Common Errors and Solutions

Missing Income

If you forgot to report income, gather the necessary information, such as invoices or bank statements, and include it in your amended return. Ensure you accurately report the amount and source of the income.

Double-check your records to ensure you haven’t overlooked any additional sources of income, such as interest from savings accounts or dividends from investments.

Incorrect Deductions

If you claimed incorrect deductions, review your expenses and ensure they meet the eligibility criteria. Remove any disallowed expenses and add any overlooked legitimate deductions.

Consult HMRC’s guidelines or seek advice from a tax professional if you’re unsure whether certain expenses are deductible.

Inaccurate Figures

If you input incorrect figures, double-check your calculations and ensure all numbers are accurate before submitting your amended return.

Review your original tax documents, such as P60 forms or bank statements, to verify the accuracy of your financial information. If you discover discrepancies, correct them before filing your amendment.


Keep thorough records of all amendments made to your tax return, including copies of any correspondence with HMRC or supporting documents. These records will be invaluable in case of any future queries or audits.

Organize your documents in a secure location and retain them for the appropriate retention period. By maintaining comprehensive records, you can demonstrate your compliance with tax regulations and respond effectively to any inquiries from HMRC.


Amending your self-assessment tax return doesn’t have to be daunting. By following these simple steps and rectifying any errors promptly, you can ensure your tax affairs remain in order and avoid potential penalties. Remember, it’s always best to be proactive and correct mistakes as soon as they’re identified.

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