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Don’t Miss the Self-Assessment Filing Deadline

The deadline for filing your online self-assessment tax return is the 31st of January following the end of the tax year. The tax year ends in April, which in theory gives you nine months to get your act together. However, we know from experience that this is the kind of task that gets inexplicably harder as the deadline approaches, so we always advise our clients to get it out of the way as early as possible.

At the time of writing, the self-assessment deadline is weeks rather than months away, so in this article we’ll look at what you need to do if you haven’t filed yet, and what happens if you don’t get it done on time.

Who needs to file a self-assessment tax return?

As a general rule, anyone who receives income that is not taxed at source will need to complete a self-assessment tax return. If you’re self-employed, or a Limited company director, you’ll need to report the income you receive from your business. Other examples include income from rental properties or investments, or income earned abroad.

What happens if you miss the deadline?

Late filing

Late payment


Miss filing deadline




30 days late

5% of tax due

3 months late


Daily penalty £10 per day for up to 90 days (max £900)

6 months late


5% of tax due or £300, if greater*


6 months late

5% of tax outstanding at that date

12 months late


5% or £300 if greater*, unless the taxpayer is held to be deliberately withholding information that would enable HMRC to assess the tax due.


12 months late

5% of tax outstanding at that date

12 months & taxpayer deliberately withholds information


Based on behaviour:

·         deliberate and concealed withholding 100% of tax due, or £300 if greater.

·         deliberate but not concealed 70% of tax due, or £300 if greater.

Reductions apply for prompted and unprompted disclosures and telling, giving and helping.

If you miss the filing deadline, whether you owe tax or not, you’ll receive an automatic £100 fine. HMRC can also impose an additional penalty of £10 per day for up to 90 days, increasing the potential cost to £1,000. There are further penalties that could be imposed after 6 months, and after 12 months.

If you have tax to pay:

If you owe tax and you pay late, HMRC will charge interest on the amount you owe. this will be in addition to penalties for filing your tax return late.

Reasonable excuses

If you do miss the filing deadline, you may be able to appeal the penalties if you have what HMRC deem to be a “reasonable excuse”. There is no exhaustive list of acceptable reasons, and each case is considered individually, but HMRC has published a list of excuses that it believes would be reasonable:

  • 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 HM Revenue and Customs (HMRC) online services

  • A fire, flood or theft prevented you from completing your tax return

  • Postal delays that you could not have predicted

  • Delays related to a disability or mental illness you have

  • You were unaware of or misunderstood your legal obligation

  • You relied on someone else to send your return, and they did not


If HMRC accepts that your reason for late filing is a reasonable excuse, they will still expect you to file your return as soon as possible after the deadline.

HMRC also state that the following will not be accepted as reasonable excuses:

  • Your cheque bounced or payment failed because you did not have enough money

  • You found the HMRC online system too difficult to use

  • You did not get a reminder from HMRC

  • You made a mistake on your tax return

If your self-assessment for tax year 2021/22 has not yet been filed, it’s important to take action immediately. If you’re unsure what you need to do, or you need advice your accountant will be able to help.

If you have questions or if we can help in any way, please call our expert team on 01296 468483, or email

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