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.

There’s a different process if you need to report foreign income.

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.


For the 2022 to 2023 tax year, you’ll 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’ll need to write to HMRC.

Online tax returns

You must wait 3 days (72 hours) after filing before updating your return.

  1. Sign in using your Government Gateway user ID and password.

  2. From ‘Your tax account’, choose ’Self Assessment account’.

  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 return you want to amend.

  7. Go into the tax return, make the corrections and file it again.

Paper tax returns

For the main Self Assessment tax return, call HMRC and request form SA100. 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 ‘amendment’ 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

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.

Write to HMRC

You must contact HMRC in writing if you’ve missed the deadline to make changes or you need to make a change to another tax year.

You’ll also need to write HMRC a letter to:

  • claim overpayment relief
  • report income you did not include in your tax return

You can claim a refund up to 4 years after the end of the tax year it relates to.

What to include

You must include:

  • the tax year you’re correcting
  • why you think you’ve paid too much or little tax
  • how much you think you’ve over or underpaid
  • your signature (no one else can sign on your behalf)

If you’re making a claim, also include in your letter:

  • that you’re making a claim for overpayment relief
  • proof that you’d paid tax through Self Assessment for the relevant period
  • how you want to be repaid
  • that you have not previously tried to claim back this refund
  • a signed declaration saying that the details you’ve given are correct and complete to the best of your knowledge

Changes to your bill

You’ll 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, sign in using your Government Gateway user ID and password and choose ‘View statements’ from the left-hand menu.

If you’re owed tax

To claim a refund, go to ‘Request a repayment’ from the left-hand menu within your HMRC online account. Allow 4 weeks for your refund to be sent to your bank account.

You may not get a refund if you have tax due in the next 35 days (for example for a payment on account). Instead, the money will be deducted from the tax you owe.

If you need to pay more tax

Your updated bill will also show:

If you sent an updated paper return

HMRC will usually send you an updated bill within 4 weeks.

It’s taking longer than usual to process changes. You can check when you can expect a reply from HMRC.

They’ll pay any refund directly into your bank account, as long as you include your bank details on your tax return.