So, Can You Amend a Tax Return After Filing?
Filing your tax return can feel like a relief—until you realise you’ve made a mistake. Maybe you forgot to include some income or claimed an expense incorrectly. If that’s the case, you might be wondering: Can you amend a tax return after filing? The short answer is yes, but there are clear rules and time limits to follow.
Understanding how and when to make changes is important if you want to stay compliant and avoid potential penalties.
When Can You Make Changes?
HMRC allows individuals to make amendments to their Self Assessment tax return within 12 months of the original filing deadline. For example, if you submitted your 2022–23 return online by the 31 January 2024 deadline, you can amend it until 31 January 2025.
This window gives you time to correct errors such as:
- Missing income (e.g. rental, freelance, or foreign earnings)
- Incorrect expense claims
- Wrong figures or mismatched information
- Overlooked allowances or reliefs
After the 12-month period ends, changes become more difficult. You would then need to make a claim for “overpayment relief” instead, which has stricter rules and longer processing times.
How to Amend a Submitted Tax Return
Amending a return depends on how you filed it. If you submitted it online using HMRC’s online Self Assessment system, log in to your account and choose the relevant tax year. Then select “Amend Return” to make changes.
For paper returns, you’ll need to write to HMRC, clearly stating what needs to be corrected and why. You should include the revised figures and any supporting documents.
Once submitted, HMRC will process the amendment. If the result changes the amount of tax you owe or are owed, they’ll adjust your bill or issue a refund.
What Happens If You’re Due a Refund?
If the amendment results in a lower tax bill than what you originally paid, HMRC will normally issue a refund. However, they won’t process it immediately. It may take several weeks, especially during busy periods.
To speed things up, ensure your bank details are up to date and submit your correction as soon as you identify the error. Refunds are paid directly into your account if you requested it when filing.
What If the Error Was Significant?
In some cases, an incorrect tax return can raise flags with HMRC, especially if the error leads to a large underpayment. If the mistake was unintentional and you fix it promptly, HMRC is more likely to accept it without penalties.
However, if they believe the mistake was deliberate or careless, they may investigate further. This could result in fines or interest charges. That’s why it’s important to double-check your figures—or better still, let a professional review them.
You can learn more about how tax returns are handled and reviewed before submitting changes.
Should You Get Professional Help?
While it’s possible to amend a return yourself, many people choose to work with an accountant. An experienced tax professional can help you:
- Identify errors you may have missed
- Ensure the amendment is correctly submitted
- Prevent issues with HMRC in the future
- Clarify whether additional steps are required
If you’re running a business or dealing with more complex income, getting support often saves both time and money.
How TRW Accountants Can Help
At TRW Accountants, we regularly help clients fix errors on submitted returns. Whether your amendment is simple or complex, we make sure everything is handled correctly and in line with HMRC’s guidelines. We also assist with full accounting services and bookkeeping, so your records stay accurate all year round.
If you’re not sure whether your return needs changing, we’ll review it and explain your options. You don’t have to deal with HMRC alone—contact us today to get it sorted.