Updating Your Tax Return: When You Can Make Changes

This guidance explains when a Self Assessment tax return can be updated and the time limits that apply. It is relevant for taxpayers who have already submitted a return and later realised something needs correcting.

HMRC allows changes within specific deadlines. Understanding those limits helps avoid unnecessary penalties or compliance issues.

Steps to Update a Self-Assessment Return After Filing

There are special rules to follow if you have submitted a Self-Assessment return and subsequently realise you need to change it. For example, this can happen if you made a mistake like entering a number incorrectly or missed information from the return.

If you filed your return online, you could amend your return online as follows:

1. Sign in to your personal tax account using your Government Gateway user ID and password.
2. From ‘Your tax account’, choose ’Self-Assessment account’ (if you do not see this, skip this step).
3. Choose ‘More Self-Assessment details’.
4. Choose ‘At a glance’ from the left-hand menu.
5. Choose ‘Tax Return options’.
6. Choose the tax year for the year you want to amend.
7. Go into the tax return, make the corrections and file it again.

You must wait three days (72 hours) after filing before updating your return. If you opted to file your return on paper, you will need to download a new return and fill in the pages that you wish to change and write ‘amendment’ on each page. You must also include your name and Unique Taxpayer Reference on each page and then send the corrected pages to the address where you sent your original return.

If you used commercial software to submit your Self-Assessment return, then you should contact your software provider in the first instance. If your software provide cannot help, then you should contact HMRC or seek guidance from a tax specialist in London familiar with post-submission corrections.

When Can You Update a Tax Return?

Once a Self Assessment tax return has been submitted, it can usually be amended within a set period. This allows taxpayers to correct errors or omissions without needing to make a separate disclosure.

Updates are commonly needed where income was missed, figures were entered incorrectly, or reliefs were not claimed at the time of filing.

Time Limits for Amending a Return

In most cases, you can amend an online tax return within 12 months of the original filing deadline.

After this window closes, changes are no longer made by amending the return itself. Different procedures apply, and HMRC may need to be contacted directly, often with supporting explanations prepared by a tax consultant in London where the position is complex.

What Happens If the Deadline Has Passed?

If the amendment deadline has passed, HMRC may still accept corrections, but the process is more formal and depends on the circumstances.

Where tax has been underpaid, interest may be charged from the original due date. In some cases, penalties can apply if errors are not corrected promptly.

Why Accuracy Still Matters After Filing

Submitting a return does not close the matter completely. HMRC can review returns after submission, and discrepancies may be queried later.

Correcting mistakes within the allowed time limits can reduce the risk of further action and ensure the tax position is accurate.

HMRC Guidance on Amending Tax Returns

HMRC explains how and when a tax return can be amended, including time limits, on
GOV.UK.

Can You Still Update Your Tax Return?

Whether an update is still possible will depend on when the return was originally filed and whether the amendment deadline has already passed. For individuals and businesses in Fulham Broadway and nearby areas such as Parsons Green and Sands End, CIGMA Accounting can review the filing timeline and confirm whether an amendment can still be made or if alternative steps are needed.