What to do if you missed the Self Assessment tax return online filing deadline

Self Assessment tax return late-filing penalties If you missed the Self Assessment tax return filing deadline, there’s an automatic late-filing fixed penalty of £100. You’ll need to pay it even if there’s no tax to pay…

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Last Updated: 8th February 2024

Self Assessment tax return late-filing penalties

If you missed the Self Assessment tax return filing deadline, there’s an automatic late-filing fixed penalty of £100. You’ll need to pay it even if there’s no tax to pay or you pay any tax due on time. Then:

  • After three months, there is an additional penalty of £10 per day for up to 90 days (ie a maximum penalty of £900).
  • After six months, there’s a further penalty of 5% of the tax due or £300, whichever is higher. This is on top of the penalties already detailed above.
  • After 12 months, another 5% or £300 charge is payable, whichever is higher, in addition to the previous penalties already mentioned.

Appealing Self Assessment late-filing penalties

You may be able to appeal your £100 Self Assessment tax return late-filing penalty, if you have a valid reason. An example could be the death of your partner or close family member or you had a serious illness or was hospitalised in the weeks leading up to the Self Assessment tax return online filing deadline.

Other valid reasons can include a delay caused by your disability or a serious computer or software problem you experienced while trying to complete or file your Self Assessment tax return online. If you encountered serious issues with HMRC’s online-filing services, your late-filing penalty could also be waived.

Need to know! Claiming that someone else failed to file your return before the deadline isn’t a valid excuse, neither is finding it hard to use HMRC’s online filing system or claiming you didn’t know when the deadline was.

If you have a valid reason, you should appeal your late-filing penalty within 30 days of your penalty notice being issued, although HMRC considers late appeals in special circumstances.

If HMRC sends you a penalty letter, you can either use the appeal form that comes with it or follow the alternative instructions explained in the letter. HMRC may ask for evidence of your claims and there are no guarantees that your appeal will be accepted.

What action should you take right now? 

File your Self Assessment tax return as soon as you can, preferably. The more you delay, potentially, the higher your penalty, so gather together all of the information you need and get on with completing and filing your Self Assessment tax return.

Sometimes people miss the deadline because their income and expenses are more complex, which makes it harder to complete their tax return, but that’s no reason to delay. What you can do is complete your Self Assessment tax return using the most accurate and reliable figures available to you. If possible, you could base your figures largely on last year’s numbers.

You then have many months to update your tax return with your actual figures when you have them. You’re OK to do this, as long as you explain that your figures are reliable provisional estimates and give a date when your Self Assessment tax return will be updated. You simply tick a box in your main SA100 tax return to declare that you’ve given estimated figures. When you do update your tax return, your tax bill will be amended accordingly.

5 ways to prevent late-filing problems next year

1. Use accounting software

Undoubtedly, using accounting software regularly to enter details of your income and any costs that you wish to claim as tax expenses will make completing your Self Assessment tax return far quicker and easier. If you’re a sole trader, it will also enable you to better understand and control your cash flow. Always make sure your figures are fully updated come the end of the month.

2. Increase your knowledge

If you struggle with any parts of the SA100 Self Assessment tax return or any supplementary pages that you need to complete and file, take time to find out what information you need to enter and where it should go.

3. Use Self Assessment filing software

Using Self Assessment filing software makes the job far easier and quicker, with mistakes less likely, too. There are many handy, time-saving shortcuts and you may even find ways to pay less tax that you weren’t aware of.

4. Fully commit to doing it earlier

You can complete and file your Self Assessment tax return as soon as the tax year ends on 5 April. You don’t have to do it on 6 April, of course, but doing it earlier, rather than waiting until January, reduces the risk that you’ll miss the deadline.

5. Set aside time long before January

Simply setting aside time in your diary (at least two or three hours if you have all of your figures to hand) long before the midnight 31 January deadline to complete your Self Assessment tax return and not letting anything affect it could make a big difference. Could be in October or November, or at a time of year when you’re less busy. To make your life much less stressful, don’t leave it until January.

Using GoSimpleTax can ensure that you enter the necessary information in the right places within your SA100 and any additional or supplementary pages. It can also save you a lot of time and effort when filling in your Self Assessment tax return. Why not start your free trial today?

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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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