9 things you should know about missing the Self Assessment tax return online filing deadline

The next Self Assessment tax return online filing deadline is midnight on 31 January 2023 and proper planning, some commitment and effort can ensure that you file on time (you can also reach out for support if you need it, of course).

Giving yourself plenty of time can not only ensure that your Self Assessment tax return isn’t late, but also that it doesn’t contain any errors and that you’re claiming all allowable expenses to which you’re entitled. Filing your Self Assessment tax return early (you can do it now) or in good time can also make your life much less stressful each January, because you’ll have one less major deadline to meet. 

So, what should you know about missing the Self Assessment tax return online filing deadline? 

1. THE DEADLINE IS THE DEADLINE

Even if you file your return online a second, minute, hour or day late, you’ll have missed the online filing deadline and you’ll need to pay a late-filing penalty.

2. THE LATE-FILING PENALTY IS £100

It’s payable to HMRC as soon as you miss the deadline. All late Income Tax payments are also subject to interest charges (3%).   

3. THE PENALTY INCREASES AFTER THREE MONTHS

If you still haven’t filed your Self Assessment tax return after three months, you’ll face an additional £10-per-day penalty, up to a £900 maximum (i.e. 90 days).

4. IT GOES UP AGAIN AFTER SIX MONTHS

If your Self Assessment tax return is six months’ late, you need to pay a further penalty of £300 or 5% of the tax owing if this is greater. That’s on top of the penalties already detailed above.

5. IT GOES UP AGAIN AFTER 12 MONTHS

If you’re a year or more late, you’ll be charged another £300 or 5% of the tax owing if this is greater, in addition to the penalties already detailed above.

6. PARTNERS CAN BOTH OR ALL BE LIABLE

If you’re part of an ordinary partnership and your Self Assessment tax return is filed late, you and your fellow partner(s) may have to pay a penalty, as detailed above, so make sure you don’t miss the deadline.

7. PENALTIES CAN BE FAR HIGHER 

If your late-filed Self Assessment tax return contains mistakes that HMRC believes are caused by a lack of reasonable care, there can be additional penalties. These can be much higher if you’ve deliberately entered false data. 

8. YOU CAN APPEAL A LATE-FILING PENALTY

Providing you have a reasonable excuse, for example, your partner or a close relative has died or you had a serious illness or were hospitalised shortly before the Self Assessment tax return online filing deadline. Other acceptable excuses include: delays caused by your disability; serious computer or software failure while preparing/filing your return online; or serious issues with HMRC’s online services.

9. YOU CAN’T BLAME SOMEONE ELSE…

Claiming that another person (e.g. your accountant) failed to file your Self Assessment tax return online before the deadline isn’t an acceptable excuse, nor is finding it hard to use HMRC’s online system or not knowing when the deadline was.

MORE INFORMATION

• Read our guide – Self Assessment tax return deadline: how to file a tax return.
• Self Assessment tax return deadlines and penalties.

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.