Realised you made a mistake on your tax return? If you're wondering, Can I amend self assessment after submission? - the answer is yes, but timing and process matter. Here’s what you need to know to fix errors and avoid penalties.
How Long Can I Amend Self Assessment After Submission?
You can amend your Self Assessment tax return within 12 months of the original filing deadline. For example, if the deadline for the 2022/23 tax year was 31 January 2024, you have until 31 January 2025 to make any corrections.
If you miss this 12-month deadline, you can still ask HMRC to make changes by writing to them. However, the process is more complicated, and HMRC decides whether to accept your request.
Can I Amend My Self Assessment Tax Return After Submission?
Yes, you can amend your Self Assessment tax return after submission. HMRC allows you to make corrections within 12 months of the original filing deadline. For example, if the deadline was 31 January 2025, you have until 31 January 2026 to make changes.
To amend your return:
If you filed online: Log into your HMRC account, select 'Self Assessment’, choose 'More Self Assessment details’, then 'Tax return options’. Select the relevant tax year, make the necessary changes, and resubmit.
You need to wait 72 hours (3 days) after filing before making any updates to your return.
If you filed a paper return: Download a new tax return form for the relevant year, complete it with the correct information, write "amendment" on each page, and mail it to HMRC.
What Happens After You Amend?
After you submit an amendment to your Self Assessment tax return, here's what to expect:
Processing Time
Online Amendments - HMRC typically updates your tax bill within three days after you make changes online.
Paper Amendments - If you sent your amendment by post, HMRC aims to process it within four weeks.
If you’re looking for more details on standard tax return processing times, check out our guide on how long does it take HMRC to process tax return online or on paper.
If You Owe More Tax
HMRC will provide a new deadline for the additional payment. It's advisable to pay promptly to avoid interest charges.
If You're Due a Refund
Once processed, you can request the refund through your HMRC online account. Refunds are usually issued within two to four weeks, depending on whether additional security checks are required.
Communication from HMRC
HMRC may contact you if they need further information to process your amendment.
Remember to keep records of all communications and monitor your HMRC online account for updates.
What We Think
Fixing mistakes on a Self Assessment tax return shouldn’t be so complicated. While HMRC allows changes for 12 months, the process isn’t always easy to navigate.
One big problem is that you can’t make quick edits after submitting your return. Instead, you have to go through an official amendment process, which can be stressful especially if it affects how much tax you owe or a refund you’re expecting.
Another issue is how long it takes HMRC to process changes. Online updates usually happen within a few days, but paper amendments can take weeks. If you need to make changes after the 12-month deadline, you have to write to HMRC, and they might not accept your request.
A simpler way to correct mistakes, like a short grace period for quick fixes, would make things much easier for taxpayers. Until then, the best way to avoid these headaches is to double-check your tax return before submitting it and keep detailed records of your income and expenses throughout the year, so you don’t have to scramble for corrections later.
How JAFA Can Help
JAFA makes tax returns stress-free by:
Helping you review your tax return before submission so you catch mistakes early and avoid amendments.
Providing clear guidance on Self Assessment rules to prevent confusion about deadlines and corrections.
Ensuring your tax records are accurate and well-organised, so you’re not scrambling for corrections later.
If you do need to amend your return, JAFA can guide you through the process and help you understand what to expect. Whether it’s getting your taxes right the first time or fixing an issue, we help you stay compliant while reducing stress.
Contact our expert accountants in Birmingham, UK, either by booking a FREE discovery call or calling us on +44 121 227 6277.
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