How to Amend a Self Assessment Tax Return

Short answer: yes. You can amend a Self Assessment tax return up to 12 months after the 31 January filing deadline. A 2024–25 return can be changed until 31 January 2027, and a 2025–26 return until 31 January 2028. If you filed through software, you make the change in that software and send it again.

How long do you have to amend a tax return?

You have to wait 72 hours (3 days) after filing before you can amend a return in HMRC's online service.

How to amend your return

If you filed with DTax Filer

1. Sign in and open the return you submitted.
2. Choose to amend it and correct the figures.
3. Check the new tax calculation.
4. Submit the amended return to HMRC online.

Amendments are included in the price of your return.

Sign in to amend your return

If you filed through HMRC's online service

Sign in to your Self Assessment account, go to "Tax return options", choose the tax year, then go into the return, make the corrections and file it again.

If you filed with other software

GOV.UK says to contact the software provider for help correcting the return. If the software can't make the correction, contact HMRC.

If you filed on paper

Get a new SA100 or the supplementary pages you need, and send HMRC the corrected pages. Write "amendment" on each page and include your name and UTR. Send them to the address on your Self Assessment paperwork or, if you can't find it, to Self Assessment, HM Revenue and Customs, BX9 1AS.

What happens to your tax bill

• Your bill is updated. If you amend online, GOV.UK says you see the amended bill straight away, and within 3 days your statement shows the difference from the old bill and any interest.
• If you owe more, the updated bill shows when to pay it, and whether your payments on account have changed. Interest is charged on tax paid late.
• If you paid too much, you may be able to claim a refund.

After the 12 months have passed

Once the amendment window has closed you can't change the return yourself. Instead you write to HMRC:

• to tell them about income you left out, or
• to claim overpayment relief if you paid too much tax. You can claim up to 4 years after the end of the tax year it relates to.

An overpayment relief claim has to contain specific details and a declaration that you sign yourself. An agent can't sign it for you, and HMRC rejects claims that leave anything out. GOV.UK lists what the letter must include.

Amending is different from filing late

Amending corrects a return HMRC already has. If you haven't sent the return at all, it is late, and penalties start at £100 the day after the deadline. See filing a late or amended tax return for the penalties and how to file an earlier year.

Frequently asked questions

How long after filing can I amend my tax return?

From 72 hours after you file, until 12 months after the 31 January filing deadline for that tax year.

Is there a penalty for amending a tax return?

HMRC doesn't charge for an amendment. If it means you owe more tax, you pay the extra, plus interest from the date it was due.

Can I amend a return for an earlier year?

Only if that year is still inside its 12-month window. For older years you write to HMRC, and you can claim overpayment relief up to 4 years after the end of the tax year.

I filed with other software. Can I amend it in DTax Filer?

GOV.UK's advice is to go back to the software you filed with. If that isn't possible, contact our support team and we'll tell you what your options are.