Making a mistake on your Self Assessment tax return can be worrying, but you do not necessarily need to panic. If you have already submitted your tax return and later discover an error, you may be able to amend your Self Assessment tax return to correct the information.
Whether you entered the wrong income, forgot to claim an allowable expense, or made another mistake, understanding how to amend a Self Assessment return can help you correct the error and ensure you pay the right amount of tax.
Can You Amend a Self Assessment Tax Return?
Yes. HMRC allows taxpayers to make changes to a Self Assessment tax return after it has been submitted, provided the amendment is made within the applicable time limit.
You may need to amend your tax return if you discover that you:
- Entered the wrong income
- Forgot to include a source of income
- Entered incorrect business expenses
- Forgot to claim an allowable expense
- Entered incorrect personal or financial information
- Made an error in your tax relief or allowance
- Reported incorrect pension or dividend income
Correcting an error as soon as you identify it can help ensure that your tax liability is accurate.
How to Amend a Self Assessment Tax Return
If you need to amend your Self Assessment, the process is generally straightforward when using HMRC's online service.
1. Sign In to Your HMRC Account
Start by signing in to your HMRC online account using your Government Gateway details.
You will need access to your Self Assessment account and the relevant tax return that you previously submitted.
2. Select the Tax Return You Want to Change
Once you have accessed your Self Assessment account, select the tax return that contains the error.
Make sure you choose the correct tax year before making any changes. This is particularly important if you have submitted tax returns for several years.
3. Make the Necessary Changes
Update the sections containing incorrect information.
For example, if you originally reported £30,000 of self-employed income but later discover that the correct figure was £32,000, you should update the relevant income section.
Similarly, if you forgot to include an eligible business expense, you may be able to add it when making your amendment.
Make sure that the information you enter is accurate and supported by your records.
4. Review and Submit the Amendment
After making the necessary changes, carefully review the updated tax return.
The amendment may change the amount of tax you owe or the amount you are entitled to receive as a repayment.
Once you are satisfied that everything is correct, submit the amended return through HMRC's online service.
Keep confirmation of the amendment and retain your supporting records.
How Long Do You Have to Amend a Self Assessment?
Generally, you can amend a Self Assessment tax return within 12 months of the original filing deadline.
For example, if the online filing deadline for a particular tax year is 31 January, you will normally have until 31 January of the following year to make an amendment.
The exact deadline can depend on the tax year and your circumstances, so check the relevant HMRC guidance if you are unsure.
If the amendment deadline has passed, you may still have options for correcting an error. In some circumstances, you may need to contact HMRC rather than simply changing the return online.
What Happens If Your Amendment Changes Your Tax Bill?
Changing your Self Assessment return can affect the amount of tax you owe.
If You Owe More Tax
If your amended return shows that you owe additional tax, you should arrange payment as soon as possible.
Depending on when the error is corrected and when the additional tax is paid, interest may apply.
If You Have Overpaid Tax
If your amendment shows that you paid too much tax, you may be able to claim a repayment from HMRC.
Make sure your repayment details are correct and keep records of the amended return.
Do You Get a Penalty for Amending a Tax Return?
Simply correcting an honest mistake does not automatically mean you will receive a penalty.
However, the circumstances surrounding the error matter. For example, penalties can apply where HMRC determines that information was deliberately inaccurate or where tax was underpaid because of careless or deliberate behaviour.
If you discover that you have made a significant error, correcting it voluntarily and promptly can be important.
What If You Made a Mistake Several Years Ago?
If you have discovered an error from a previous tax year but the normal amendment period has already passed, you may not be able to amend the return through your online HMRC account.
However, depending on the circumstances, you may be able to make a claim or contact HMRC to explain the situation.
Do not simply ignore an old error because the standard amendment deadline has passed. Getting professional advice can help you understand the appropriate next step.
Common Mistakes When Amending Self Assessment
When correcting a tax return, taxpayers should avoid making further errors. Common mistakes include:
- Selecting the wrong tax year
- Changing figures without checking supporting records
- Forgetting to update related information
- Claiming expenses that are not allowable
- Entering income twice
- Failing to check the revised tax calculation
- Missing the deadline for making an amendment
Keep copies of your original and amended records so you can clearly see what was changed and why.
Need Help to Amend Your Self Assessment?
If you are unsure how to amend your Self Assessment tax return, professional support can make the process easier.
MyIVA provides online Self Assessment tax filing services for individuals, sole traders, and small business owners across the UK. If you have submitted your tax return and discovered an error, getting the figures reviewed before making changes can help you avoid further mistakes.
Whether you need help correcting income, expenses, tax reliefs, or other information, MyIVA can help you understand the amendment process and keep your Self Assessment tax affairs organised.
Need to amend your Self Assessment tax return? Get professional online tax filing support from MyIVA and make sure your tax return is corrected accurately.
