I’ve Missed The Self-Assessment Tax Deadline – Can I Avoid A Fine?

By midnight on the 31st October or 31st January, you need to file a Self Assessment tax return for the previous tax year. Thousands of people miss the Self Assessment tax deadline and suffer late tax…

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Last Updated: 8th February 2024

By midnight on the 31st October or 31st January, you need to file a Self Assessment tax return for the previous tax year.

Thousands of people miss the Self Assessment tax deadline and suffer late tax return penalties every year. But there are two sides to late penalties. One is for the failure to submit a Self Assessment tax return. The other is for not paying the tax bill itself.

Follow our guidance, and you may avoid fines for a missed tax bill payment or tax return deadline…

What Do I Do If I’ve Missed The Self Assessment Tax Deadline?

There are two deadlines to bear in mind: one for paper returns (31st October) and the other for digital (31st January the following calendar year).

If you’ve missed the paper tax return deadline, you’re still able to file it online. Don’t send a paper return after the October cut-off date, because you will be fined in the post.

You must also ensure you register for the Self Assessment tax return, if you haven’t done so already, by the 5th October. HMRC will give you a 10-digit tax code in the mail. This is your Unique Taxpayer Reference (UTR) number, which will be used on all future correspondence between you and HMRC, including your welcome SA250 letter confirming you’ve registered.

However, assuming you have missed these deadlines completely, there are two things you need to do as soon as possible:

  • Complete and file your Self Assessment tax return through HMRC’s web portal or tax software.
  • Pay your tax bill. You should be notified that a payment is outstanding within days of submitting your tax return, with any relevant fines also outlined. Even if you are not notified, you need to pay the tax as soon as possible to minimise the penalties and interest.

What If I Can’t Afford To Pay The Bill?

If you can’t afford to pay your tax bill, contact HMRC immediately.

They may be lenient and allow you to pay in instalments over a set period. HMRC often prefer to have the payments arranged this way, rather than issue further fines if you’re unable to cover the initial cost.

Call 0300 200 3822 – the Self Assessment payment helpline – and speak to a representative if you can’t afford to pay your tax bill. It’s open between 8am to 8pm on weekdays, and 8am to 4pm on Saturday.

What Is The Penalty For Filing A Late Tax Return?

A late tax return penalty starts as an immediate £100 fine, but can increase the longer you leave the Self Assessment tax return unfiled – up to a maximum 12-month threshold.

Here’s what happens if you file your tax return late, assuming you miss the 31st January midnight deadline:

  • An immediate £100 fine is issued.
  • For the following three months, up until the 1st May, £10 is charged every day for a maximum of 90 days. This can, therefore, total an extra £900 on top of the immediate fine.
  • If you don’t pay by the 1st August, you’re due an additional £300 fine or 5% of the tax you owe – whichever is the larger sum.
  • A year later (1st February, 12 months after the original missed deadline) you are charged another £300 or 5% of the tax owing.
  • Ultimately, payment could be around £1,600 for filing a Self Assessment tax return one year after you’re meant to.

On the other hand, this is the fee timeline for delayed tax payments:

  • 30 days after the deadline (1st March), you are charged 5% of the outstanding tax bill.
  • If you still haven’t paid by the 1st August, another 5% is added to the new tax bill – i.e. your initial tax bill plus the first 5% charge.
  • Then by the 1st February, HMRC will ask for another 5% for the total tax owed that day.
  • Whatever the final amount maybe, you are also charged 3% interest on the charges you’ve accrued. So if, for example, the fines have totalled £400, you have to pay £412 as well as the outstanding tax bill.

Can I Appeal The Fine?

Yes – HMRC will take mitigating factors into account if you have missed the Self Assessment tax deadline. They know that everything doesn’t always run smoothly, but you must have what is deemed a ‘reasonable excuse’.

They include:

  • A partner or close relative died shortly before the deadline was due.
  • Your computer or tax software failed in the hours prior.
  • A serious illness or injury prevented you from submitting.
  • HMRC’s services faced issues as you were submitting.
  • A flood, fire or theft occurred, which prevented you from submitting.

Follow the instructions in the penalty letter that HMRC sent you – or the steps on this GOV.UK page. This must be done within 30 days of the penalty notice being issued. The government will ask for proof of your reasonable excuse. That’s how to appeal against a late tax return penalty.

Taking It All Into Account

Under Self Assessment, you still have options if you’ve missed your tax return or payment deadline. Whether that’s arranging a repayment schedule overtime or making an appeal, HMRC are usually considerate. Please note that they won’t normally accept an appeal until the tax return has been submitted.

But the next step is to get in touch with them without delay. It’s in your interest, and it can stop more fines and interest accumulating.

GoSimpleTax software can help you complete and submit the right Self Assessment return before it’s due each year. Try our free trial to explore some of our features. With pointers, reminders and real-time updates, you’ll never be in the dark about your tax responsibilities again.

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Blog content is for information purposes and over time may become outdated, although we do strive to keep it current. It's written to help you understand your Tax's and is not to be relied upon as professional accounting, tax and legal advice due to differences in everyone's circumstances. For additional help please contact our support team or HMRC.

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