Self Assessment tax returns
If you need to change your return
You can make a change to a tax return after you filed it, for example because you made a mistake.
Your bill will be updated based on what you report. You may have to pay more tax or be able to claim a refund.
Updating your tax return
You can correct a tax return within 12 months of the Self Assessment deadline, online or by sending another paper return.
Example
For the 2022 to 2023 tax year, you鈥檒l usually need to change your return by 31 January 2025.
If you miss the deadline or if you need to make a change to a return from an earlier tax year you鈥檒l need to write to HMRC.
Online tax returns
You must wait 3 days (72 hours) after filing before updating your return.
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From 鈥榊our tax account鈥�, choose 鈥橲elf Assessment account鈥�.
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Choose 鈥楳ore Self Assessment details鈥�.
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Choose 鈥楢t a glance鈥� from the left-hand menu.
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Choose 鈥楾ax return options鈥�.
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Choose the tax year for the return you want to amend.
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Go into the tax return, make the corrections and file it again.
Paper tax returns
For the main Self Assessment tax return you can:
You can download all other forms and supplementary pages.
You then need to send the corrected pages to the address on your Self Assessment paperwork.
Write 鈥榓mendment鈥� on each page and include your name and Unique Taxpayer Reference (UTR) - this is on previous tax returns or letters from HMRC.
If you cannot find the address, you can send your corrections to:
Self Assessment
HM Revenue and Customs
BX9 1AS
If you used commercial software
Contact the software provider for help correcting your tax return. Contact HMRC if your software is not able to make corrections.
Changes to your bill
You鈥檒l see your amended bill straight away if you updated your tax return online. Within 3 days, your statement will also show:
- the difference from the old one, so you can see whether you owe more or less tax
- any interest
To view this, and choose 鈥榁iew statements鈥� from the left-hand menu.
If you鈥檙e owed tax
You may be able to claim a tax refund.
If you need to pay more tax
Your updated bill will also show:
- the deadline for paying
- the effect on any payments on account you need to make
If you sent an updated paper return
HMRC will send you an updated bill. You can check when you can expect a reply from HMRC.
They鈥檒l pay any refund directly into your bank account, as long as you include your bank details on your tax return.
If you鈥檝e missed the deadline to change your return
You must contact HMRC in writing if you need to make changes to your tax return more than 12 months after the Self Assessment deadline. This includes making a change to an earlier tax year.
You鈥檒l also need to write HMRC a letter to:
- report income you did not include in your tax return
- claim overpayment relief (if you think you鈥檝e overpaid tax)
You can claim overpayment relief up to 4 years after the end of the tax year it relates to.
What to include
You must include:
- the tax year you鈥檙e correcting
- why you think you鈥檝e paid too much or little tax
- how much you think you鈥檝e over or underpaid
- your signature (no one else can sign on your behalf)
If you鈥檙e making an overpayment relief claim, you must also include in your letter:
- that you鈥檙e making a claim for overpayment relief
- if you鈥檝e previously made an appeal for the same payment
- a signed declaration saying that the details you鈥檝e given are 鈥榗orrect and complete to the best of your information and belief鈥�
You also need to keep evidence that you鈥檝e paid tax through Self Assessment for the relevant period as HMRC may ask for this at a later date.
If you do not include all of this information your claim will be rejected.
You can also tell HMRC how you want to be repaid in your letter.