2022-23 self-assessment deadline looming: what to do if you didn't file over Christmas

Eat, drink and be merry... and file your tax return? That's how 4,757 people chose to spend Christmas Day, according to figures from HMRC. 

The tax office has revealed it received a total of 25,769 self-assessment tax returns over the three days spanning Christmas Eve, Christmas Day and Boxing Day in 2023. That's a 17% increase on the 22,060 who filed returns over the same period in 2022. 

The most popular time to file a tax return over the period was between 12:00 and 12:59 on Boxing Day, when HMRC received 1,121 returns. 

It might just be that the bank holiday was the only time some self-employed people had to get this big bit of life admin sorted. But if you still haven't filed your 2022-23 tax return yet, it isn't too late.

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How to meet the tax return deadline

If you have untaxed income (usually from self-employment or property) you have until midnight on 31 January 2024 to file your tax return online.

Here are some tips to make the deadline and avoid a last-minute panic.

Set aside time to avoid mistakes

There are still four weekends to get your return done, so schedule some time in your diary to sit down and focus on it.

Leaving it to the last minute could mean you rush and make mistakes. HMRC can impose fines for mistakes if it thinks you haven't taken 'reasonable care' in filling out the form. 

• Find out more: how to file a tax return

Check your login details

You will need your government gateway ID and password to file a tax return online, so it's best to have them handy to avoid any login delays.

Don't worry if you've forgotten or lost these details – they can be reset. This can take some time, however, so it's a good idea to test them out well ahead of the deadline, even if you're not quite ready to file yet.

Gather your paperwork

You'll need records of your earnings and any expenditure you wish to claim tax relief on, for the period between 6 April 2022 and 5 April 2023. 

Business expenses, for example, can be deducted from your taxable income. These include business travel and transport, maintaining or replacing work uniforms, office running costs such as stationery or phone bills, and the cost of business premises (including energy bills) – all of them can count as an allowable expense.

Crucially, you’ll also need your National Insurance number and Unique Taxpayer Reference (UTR) number. 

• Find out more: tax-deductible expenses

Have a plan on how to pay

The deadline to pay your tax bill is also 31 January, and if you're self-employed it's the day you'll have to make your first payment on account for the 2023-24 tax year, and a balancing payment if tax is still owed from your 2022-23 income.

If you think you might struggle to settle the bill, you might be able to apply for a Time to Pay arrangement. This will break up your tax bill into smaller instalments spread over the following months. Keep in mind that you will still incur interest on any tax you haven't paid after the 31 January deadline. 

To set up one of these arrangements, you'll need to be within 60 days after the payment deadline, owe less than £30,000, and have no pre-existing payment plans or debts with HMRC. You can set up a payment plan online or call the Payment Support Service on 0300 200 3835.

HMRC says there is no 'standard' arrangement, so the period for your instalments will be decided based on your circumstances. 

Try the Which? tax calculator

Filling out a tax return can be complicated, which is why we've partnered with SimpleTax to create an online self-assessment tool that can help you streamline the process. 

The Which? tax calculator not only helps you tot up the tax you owe, it can also suggest expenses and allowances you might have forgotten. 

Plus, when you've finished filling out your information, you can also use the tool to submit your tax return directly to HMRC.

What happens if I miss the 31 January deadline?

If you miss the deadline, you could receive an automatic £100 fine. 

After that, your potential fine will increase depending on how late you are. 

After three months, you'll be fined £10 per day (capped at 90 days), plus the initial £100 fine, to a maximum of £1,000. 

If you're more than six months late, you could receive the fine above plus £300 or 5% of the tax due, whichever is higher. 

Then, after a year, you may incur an additional £300 fine, or another 5%, plus all of the above penalties. If your case is particularly serious, you could be fined 100% of what you owe.

• Find out more: tax return late fees, explained