What to do if you missed the Self Assessment deadline

Did you miss the online Self Assessment deadline of January 31 or the post deadline of October 31? Or are you at risk of missing the deadline extension of February 28?

If you’re in this situation, you wouldn’t be alone. In fact, the HMRC reports that hundreds of thousands of people miss this deadline each year. Filing taxes can be confusing, stressful, and time-consuming.

Still, it’s fair to wonder what might happen and what you should do. Luckily, we can help. 

This guide discusses what happens when you missed the Self Assessment deadline, including:

• What happens if you missed the Self Assessment deadline.
• What to do if you miss the deadline.
• How to avoid missing it in the future. 

See also: How to do a Self Assessment tax return.

If you only file your Self Assessment tax return a couple of days late (or up to three months), you’ll receive a £100 fine from the HMRC. 

The taxes you owe will also start to earn interest. 

When you pass the three-month point, the HMRC will add a £10 fee each additional day you’re late in submitting your tax return. These extra fees can increase your penalty by £900 to £1000. 

Then, the HMRC will add further charges at the six and 12-month marks. 

To learn more about how much you have to pay in late penalties, you can estimate your penalty here. 

You can find out more about late charges with our article: How much is the penalty for filing taxes late?

As your submission grows later, you’ll likely pass the deadline to pay the taxes you owe. Late tax payments will lead to: 

• 3 months – 5% of the tax due.
• 6 months – 5% of the remaining tax due (including interest).
• 12 months –  5% of the remaining tax due (including interest).

As of January 2022, the HMRC waived the late fee for the January 31 deadline until February 28. So, if you submit your tax return before that time, you’ll only have the tax interest to worry about. 

Alternatively, if you typically submit your Self Assessment by post, but missed the October 31 deadline, you can do it online instead. To do this, you must have registered online by October 5.  

If you still want to submit a paper assessment late, you can choose to do so. But keep in mind that the same penalties apply despite a three-month sooner deadline. 

Let’s say you missed all potential deadlines. Then what do you do?

In this case: 

• Submit your late Self Assessment as soon as possible. 
• Determine your penalties and pay them. 
• If you’re late but have a reasonable excuse for it, you can appeal your penalty. 

It’s up to the officer reviewing your case to accept or reject your reasonable excuse. But, you may be able to wave your penalty if: 

• A relative died just before the deadline. 
• You were seriously ill or in the hospital.
• You had technical issues. 
• You had service issues with the HMRC. 
• There was a flood, fire, or theft that got in the way. 
• You experienced unexpected post delays. 

If you hired an accountant to file your taxes and they failed to do it, this wouldn’t count as a reasonable excuse. 

Missing your Self Assessment deadline can be stressful and risky. The late fees will lead to unexpected and avoidable expenses that could hurt your business’ finances. 

With that said, we can offer a few tips to avoid doing it in the future. 

First, be sure to understand the deadlines for filing your Self Assessment tax return. 

Typically you’ll need to: 

• Register for Self Assessment by October 5.
• Submit your paper tax return through the post by October 31. 
• Submit your online tax return by January 31.
• Pay your taxes by January 31 (though you do have until April 1 to pay without being charged a late filing penalty). 

Put these dates in your calendar and set yourself reminders a few months, weeks, and days in advance. By doing this, you can prepare ahead of time, so the dates don’t creep up on you. 

Planning for your Self Assessment submission can make the process easier, quicker, and less stressful. This way, you’ll be less likely to submit it late. 

Consider setting some of your income aside each month to cover the upcoming tax expenses. With these savings, it’ll be easier to pay what you owe. 

Plus, be sure to keep organised and updated financial records. If you update and check your bookkeeping regularly, you won’t have to scramble for the necessary information. Instead, it’ll only take a few minutes to file your taxes. 

You don’t have to handle your Self Assessment tax return alone. Though you may not need an accountant for this process, hiring one can take a lot of the stress off your shoulders. 

An accountant offers expertise to get your financial data in order. They can also file your Self Assessment for you, making the deadline more manageable. 

Learn more with our article on how to find an accountant for your business. 

On top of that, modern accounting software like Countingup can help you prepare for tax season year-round. 

Countingup is a business current account and accounting app rolled into one. It automates time-consuming bookkeeping admin for thousands of self-employed people across the UK. 

Countingup can simplify your tax process with: 

• Year-round tax estimates.
• Making Tax Digital compliance (See: What is Making Tax Digital?).
• Easy financial data sharing with your accountant without worrying about duplicates, errors, or lags.

Save yourself hours of accounting admin so you can focus on growing your business. 

Start your three-month free trial today. 

Now that you know what to do when you missed the Self Assessment deadline, you can handle the situation with ease and avoid it in the future. 

Just remember to: 

• Know the deadlines. 
• Determine your penalty. 
• Apply for relief if you have a reasonable excuse. 

You may want to learn more about organising your self-employed finances for a more efficient and stress-free future tax experience. If so, check out our article on how to organise your business finances.