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Self Assessment Corrections after Filing

There may be circumstances when you need to change a tax return after you filed it. This help guide explains how to make Self Assessment tax return corrections if you make an error.

SELF ASSESSMENT CORRECTIONS: There are deadlines for correcting a Self Assessment tax return:

  • Tax Return Changes for 2020/21 Tax Year: Deadline is January 31st 2023
  • Tax Return Changes for 2021/22 Tax Year: Deadline is January 31st 2024

You must write to HM Revenue and Customs if you miss any of these deadlines. The same process applies if you need to make tax return corrections for any earlier tax years than these.

HM Revenue and Customs update your bill based on what changes and errors you report.

In some cases you will have to pay more tax and in others you may qualify to claim a tax refund (rebate) instead.

How Can You Update a Tax Return?

The method for updating tax returns will depend on how it got filed in the first place. Follow these steps to update a tax return online or make changes to the paper version.

7 Steps to Update a Tax Return Online

  1. Log in to your HM Revenue and Customs Government Gateway online account.
  2. Select ‘Self Assessment account‘ from ‘Your tax account‘ (skip this section if it does not show).
  3. The next step is to choose ‘More Self Assessment details‘.
  4. Then select ‘At a glance‘ showing in the left-hand menu.
  5. Choose ‘Tax return options‘.
  6. You then need to select the correct tax year for the tax return that you want to amend.
  7. Step seven is to going into the relevant tax return and making the corrections. File it once more after you make the changes.

Note: A different process applies for ‘reporting undeclared income‘ (e.g. renting out property abroad). You must inform HM Revenue and Customs without delay if you made money that you need to pay tax on.

Update a Paper Tax Return

You should write the word ‘amendment‘ on every page that you corrected. Remember to include your name and Unique Taxpayer Reference as well. Your UTR shows on any previous tax returns or letters that you received from HMRC.

Commercial Software for Self Assessment Tax Returns

It is best to contact the provider if you use commercial software for Self Assessment tax returns. They should be able to help you correct your tax return. Contact HMRC if they are unable to make the changes for you.

Note: HMRC does not endorse or recommend any one product or service as the best commercial software for Self Assessment. But, they do have a list of Self Assessment commercial software suppliers.

Changes to Tax Return 2019/20 (or before)

You need to write to HMRC to make changes to a tax return for the 2019 to 2020 tax year or earlier. Remember to include the following information in the letter:

  1. The specific tax year that you want to correct.
  2. The reason why you believe you paid either too much or too little tax.
  3. The amount that you think you overpaid or underpaid.

You can only claim a tax refund up to four (4) years after the end of the tax year that it relates to. In this case, you must include some extra information in your letter to HMRC, such as:

  • A note that shows you are making a claim for ‘overpayment relief’.
  • Some proof that shows you paid tax through Self Assessment for the relevant period.
  • The method that you prefer for the repayment.
  • Confirmation that you did not try to claim back this tax refund Self Assessment before.
  • A signed declaration that says the details that you are providing are correct and complete to the best of your knowledge.

Amended Changes Showing on a Tax Bill

As a rule, it is quicker to file an amendment to your tax return online. You will see the amended changes to your bill straight away. It then takes around three (3) working days for your statement to show:

  • The different balance to the previous one. That means you will see whether you owe more tax or less.
  • Any interest due to the changes made.

Note: Choose ‘View statements‘ from the left-hand menu after logging in to your account to view the changes.>

How to Claim a Tax Rebate Online

Select ‘Request a repayment‘ from the left menu inside your HMRC online account to claim a refund. But, it may take up to four (4) weeks for a tax rebate to show up in your bank account.

Note: The refund may not show if you have tax due in the next 35 days (e.g. payment on account). The money gets deducted from the tax you owe instead.

If More Tax is Owing

In cases where more tax is due after you amend a tax return, the updated bill will also show:

  1. The deadline for the payment.
  2. The effect it may have on any ‘tax payments on account‘ and what you need to do.
After Sending an Updated Paper Tax Return

HM Revenue and Customs send the updated bill within four (4) weeks and pay any refund into your bank account. But, this can only happen if you remembered to include your bank details on the tax return.

Process of Self Assessment Error Correction in United Kingdom