What to do if you miss the tax return deadline

The tax return deadline for online tax returns is 31st January. In very rare situations, HM Revenue & Customs (HMRC) may give you an extension for your tax return, but this isn't typical.

In addition, any tax should be paid by 31st January too, and if you are required to make payments on account additional tax could be payable on that date, as well as 31st July.

What are the penalties for late tax returns?

If HMRC asked you to complete a tax return for 2023/24 and you missed the 31st January deadline, you will automatically be fined £100, regardless of whether you're just one minute late or how small your tax liability is. Even if you are due a tax refund, a penalty would normally apply.

Penalties for filing your self-assessment tax return late are:

• 1 day late – Automatic fixed penalty of £100. 
• 3 months late – £10 per day up to a 90 maximum of £900.
• 6 months late – £300 or 5% of the tax due, whichever is higher. 
• 12 months late - £300 or 5% of the tax due, whichever is higher.

In serious cases, you may even be asked to pay up to 100% of the tax due instead. These penalties are in addition to one another, so the minimum late filing penalty for a tax return that is 12-months late will be upwards of £1,600 depending on the tax liability. 

Penalties for late payment of tax are:

• 30 days late – 5% of tax due
• Six months late – 5% of outstanding tax due at that date
• 12 months late – 5% of outstanding tax due at that date

It is also important to bear in mind that interest will be charged on top of these penalties on the outstanding tax due, plus any outstanding penalties due.

My tax return is late, what should I do?

Firstly, you need to consider if the tax return is required or if you have a legitimate reason for the delay:

Cancelling a tax return

You can use the ‘ask HMRC online’ option and speak to a webchat advisor or complete a form online. If HMRC agrees, you no do not need to file a return and any penalties issued for missing the deadline should be cancelled

Remember to note down who you spoke to and when, what outcome is expected and when you will receive their decision.

HMRC is unlikely to withdraw a return if you have been self-employed at any point during the tax year – even a very short time will count. Typically, you will only have two years from the end of the tax year for which the return is due to request its withdrawal, but it's always better to deal with your tax affairs swiftly. 

Reasonable excuses

If you have a good reason for the delay, you may be able to appeal against the penalty. 

HMRC lists several common examples of Reasonable Excuses on its website.

These include:

• Your partner or another close relative died shortly before the tax return or payment deadline
• You had an unexpected stay in hospital that prevented you from dealing with your tax affairs
• You had a serious or life-threatening illness
• Your computer or software failed just before or while you were preparing your online return
• Service issues with HMRC online services

What's unlikely to be reasonable excuse?

The following aren’t usually accepted as a reasonable excuse:

• you relied on someone else to send your return and they didn’t
• your cheque bounced or payment failed because you didn’t have enough money
• you found the HMRC online system too difficult to use
• you didn’t get a reminder from HMRC
• you made a mistake on your tax return

HMRC also revealed some of the most outlandish excuses it received here.

If you've missed the deadline, file your tax return as quickly as possible

If the tax return can't be withdrawn and you don't have a reasonable excuse, the next best thing is to file your tax return as soon as is practical – even if you can't afford your tax bill yet. As you've seen, the late filing penalties will increase the longer you delay. 

How long do I have to change my tax return? 

If you make a mistake on your tax return, you can amend it. To amend a tax return online you must make your changes within 12 months of the self-assessment deadline (by 31st January 2026 for a 2023/24 self-assessment tax return).  

After this deadline has passed, if you need to change your tax return, you’ll need to write to HMRC. 

Need more help?

We love working with self-employed professionals and independent business owners and if you are not receiving the service and support you deserve from your accountant then please talk to us on 01442 268000 or use our online enquiry form. We offer free initial consultations, advice, and support over the phone or via video meeting if you have any concerns about face-to-face meetings.

Last updated 1 Feb 2024 | First published 26 Jan 2018

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This article is intended to inform rather than advise and is based on legislation and practice at the time. Taxpayer’s circumstances do vary and if you feel that the information provided is beneficial it is important that you contact us before implementation. If you take, or do not take action as a result of reading this article, before receiving our written endorsement, we will accept no responsibility for any financial loss incurred.