My tax return is wrong, what
should I do?

my tax return is wrong

If you’re concerned that you may have made a mistake on your tax return, don’t panic. There are a few things that you can do to protect yourself from receiving a nasty penalty. Take a look below for GoSimpleTax’s advice:

Amend it Immediately

If you’ve noticed a mistake in your most recent tax return, you have up to twelve months to fix it. Your self assessment should be amended using the same platform through which it was submitted – for example, if you sent it online, the amendment should be made online, and if you did so via the post, your changes should be made by sending hard copies of the corrected pages (each marked “amendment” and labelled with your name and UTR number) to Self Assessment, HM Revenue and Customs, BX9 1AS, United Kingdom.

Write to HMRC

Should the aforementioned twelve months’ leeway have lapsed before you noticed the mistake, you can still contact HMRC to make changes up to four years after the relevant tax year. The letter you send should indicate the year of the tax return you’re amending, the reason for your over or underpayment and the amount thereof.

If you think you’ve overpaid, you also need to explain that you’re claiming for “overpayment relief”, provide proof that a tax payment was made for the relevant period and that you’ve not already tried to claim the amount back, express how you want to be repaid and complete a signed declaration confirming that the details you’ve given are correct and complete to the best of your knowledge.

What To Do Next

You should receive an amended bill within the next three days. If you owe anything extra, you should arrange to pay this immediately.

For future tax returns, consider utilising the GoSimpleTax app or its online tools. This software automatically alerts you of any potential miscalculation or mistake within your tax return, preventing the need for any potential future amendments and protecting you from any resulting fines.

Need help preparing your tax return?

By downloading GoSimpleTax for iOS or Android, you can save yourself hours of valuable time and prevent the stress of completing your annual tax return.

self assessment software

How GoSimpleTax Works

self assessment software


Simply register for free with your full name and email address.

self assessment software


Select the income you receive and follow the hints and tips for potential tax savings.

self assessment software


Validate your personal information when you’re happy with the figures and submit directly to HMRC to get confirmation of your submission in just a few seconds.

"Affordable and easy to use tax return software."
James K.
Web Developer
"Excellent help for self-employed people with simple accounting needs."
Michael V.
Landscape Architect
"The process was so simple, I wondered if I'd got it right!"
Kenneth S.
Minister of Religion

Who Is GoSimpleTax for?

Sole Traders

With GoSimpleTax by your side, your tax duties as a sole trader are made easier than ever before.


Manage your HMRC tax return on assets and investments easily with GoSimpleTax.

Uber & Taxi Drivers

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Ministers of Religion

Claim all tax exemptions available to Ministers of Religion and avoid being penalised for the avoidable.

Online Sellers

Usure about the tax return for eBay, Etsy, Gumtree, and Amazon sellers? GoSimpleTax has the answers.


Self-employed workers can spend more time generating income and less worrying about their tax return.


Let GoSimpleTax do the legwork for you while you focus on building your portfolio.


Stumbling over the tax return for overseas income? Let GoSimpleTax guide the way.