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The deadline for submitting your Self Assessment online, and paying any tax you owe, is midnight on the 31st January. If you prefer to submit using a paper return, the submission deadline is 31st October.

But what happens if you are late submitting your Self Assessment tax return? Unfortunately you’ll face an automatic fine from HMRC for missing the deadline. The longer you leave it before taking action, the larger the fine becomes.

If you’re brand new to Self Assessment, download our guide to learn more about deadlines and responsibilities.

Self Assessment Guide

What are the fines for late Self Assessment submission?

If you miss the deadline for filing, you will be hit by an automatic £100 fine from HMRC. Extra charges are added the longer you leave it.

Failure to submit within three months of the deadline (by the end of April), incurs an additional £10 a day fine for the next 90 days. This means the penalty will increase by £900 – bringing the total penalty to £1,000. Ouch.

If you still haven’t filed after six months or even 12 months, you will face further penalties based on the amount of tax that you owe. Interest is also charged on top of the unpaid tax.

Watch our video about when and how to pay different types of tax, including for your Self Assessment tax return.


Fines for late payment

As well as penalties for missing the Self Assessment submission deadline, there are fines for missing the payment deadline too.

Late payment Penalty
30 days late payment Your tax bill, plus an additional penalty of 5% of your tax bill
6 months late payment The above, plus 5% of that amount
12 months late payment The above, plus a further 5% of that amount

Don’t forget payments on account

Payments on account are intended to spread the cost of Self Assessment income tax and Class 4 National Insurance contributions. If your tax bill was more than £1,000 for a tax year, you’re required to make a payment on account the following tax year.

It’s basically an advance payment on next year’s bill, working on the assumption that your earnings will be the same as or higher than the previous year.

The idea behind it is so that you don’t have to pay one massive bill in January. In practice it means that you will pay 50% of the previous year’s bill as an advance against tax for the following tax year.

The deadline for your first payment on account is 31st July. Missing the deadline also incurs penalties.

What if I didn’t need to submit a tax return?

Some people are caught out by thinking that because they don’t owe any tax this year, they don’t need to submit. Sadly, this isn’t the case. Unless you tell them otherwise, HMRC expect a Self Assessment return from anyone who is registered for it.

So, unless you let them know in advance, if you fail to submit and HMRC are expecting a return, you’ll receive a penalty.


Tax return services

Is there any way to avoid fines?

HMRC will sometimes waive penalties if you have a “reasonable excuse” though they’re pretty strict on what counts.

It’s largely down to their discretion, though you may be excused if you’ve been seriously ill, suffered bereavement close to the deadline or you’ve had serious IT problems.

You can also appeal against a penalty you think was unfairly given, using a SA370 form or the online service.

Talk to one of the team about our online accounting services, including tax returns. Call 020 3355 4047, request a call back, or get an instant quote online.  

About The Author

Elizabeth Hughes

A content writer specialising in business, finance, software, and beyond. I'm a wordsmith with a penchant for puns and making complex subjects accessible. Learn more about Elizabeth.

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