Oops! Made a Mistake? How to Amend Your Self-Assessment Without Triggering an Audit

We have all been there. You have finally clicked ‘submit’ on your self-assessment tax return in London, breathed a massive sigh of relief, and made a celebratory cup of tea. Then, it hits you.

You realise you forgot to include that small invoice from last summer, or perhaps you accidentally added an extra zero to your office expenses. Your heart sinks. You might start worrying that HMRC is going to come knocking on your door or that an audit is inevitable.

At Wingate Accountants Ltd, we want to tell you one thing clearly: take a deep breath. Mistakes happen to the best of us. The good news is that the UK tax system actually has a built-in pencil and eraser phase. You can fix your errors without causing a panic, provided you follow the right steps.

Don’t Panic! HMRC Expects a Few Hiccups

HMRC knows that tax can be tricky. Their primary goal is to get the right amount of tax paid, not to punish you for a simple typo. If you spot a mistake, the worst thing you can do is ignore it and hope they don’t notice. Being proactive is your best defense against an audit. When you come forward to correct an error, it shows good faith. It tells the tax office that you are trying to be honest and accurate.

How to Fix It (The Simple Way)

If you filed your return online, the fix is usually just a few clicks away. You generally have twelve months from the original filing deadline to make an amendment.

Log Back In: Go to the government gateway where you filed.
Find the Return: Select the relevant tax year.
Amend: Click on the amend return button.
Correct the Figures: Change the specific boxes that were wrong.
Re-submit: Send it off again.

If you are past that twelve-month window, don’t worry. You can still write to HMRC to claim Overpayment Relief or disclose an underpayment. We often help our clients draft these letters so they are clear, concise, and professional.

Will This Trigger an Audit?

This is the big question we get asked in our Manchester and London offices. Usually, a simple amendment to fix a genuine oversight does not trigger a full-scale investigation. What does raise red flags is a pattern of constant changes or waiting until HMRC finds the mistake themselves. By being the one to raise your hand and say, I got this bit wrong, you are actually making yourself look like a lower-risk taxpayer.

We Are Here to Help

At Wingate Accountants Ltd, we believe that your focus should be on growing your business, not losing sleep over tax forms. Whether you are dealing with a complex portfolio or a simple self assessment tax return in the UK, we can double-check your figures before you hit send or help you fix them if you already have. If you have realised your return isn’t quite right, don’t let it sit there and worry you. Reach out to us today for a quick chat or a coffee. We’ll help you get it sorted properly so you can get back to what you do best!