The deadline to file your 2023/24 tax return and settle your bill was 31 January 2025. An estimated 1.1 million taxpayers missed the deadline this year, according to HMRC.
Not everyone is required to complete a tax return, but if HMRC was expecting one from you and you missed the deadline, you are now three months late. At this point, the penalties start to ramp up, meaning you should get your paperwork in order as soon as possible.
Late filers are charged an initial £100 penalty for missing the deadline by even one day (i.e. 1 February). After three months (1 May), you get hit with additional daily penalties of £10, up to a maximum of £900.
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After six months, a further penalty applies – either 5% of the tax due or £300, whichever is greater. The same penalty (5% or £300) applies again once you are 12 months late.
There are also penalties for paying your bill late, even if you filed on time. These include 5% of the unpaid tax at 30 days, six months and 12 months. Interest is also charged at an eyewatering rate of 8.5% (base rate plus 4%).
“Although the deadline was back in January, it's likely that hundreds of thousands of people still haven't filed their tax returns,” said Alastair Douglas, chief executive at financial services company TotallyMoney.
“While the initial £100 fine might not have been enough to encourage some to get going, from today, HMRC will start charging late filers an extra £10 per day.”
Douglas explains that any penalties need to be paid within 30 days of receiving a penalty notice. You can pay in several ways, including through bank transfer, using your debit or credit card, or by sending a cheque.
If you have a reasonable excuse for why your tax return is late, you can challenge your penalty. This could include a death or serious illness in the family, or challenges with HMRC’s online services.
Some people also put off dealing with their paperwork because they can’t afford to pay their tax bill – but this is a bad idea.
“If you’re struggling to pay your bill in full, then head over to the HMRC website where you might be able to set up a payment plan under a ‘Time to Pay’ arrangement,” Douglas said.
Who needs to file a self-assessment tax return?
If your only source of income is your salary and you are not self-employed, then you probably don’t need to file a tax return. Your income tax will be deducted from your salary before you receive it through a process called “pay as you earn” (PAYE).
Pension income is generally taxed through PAYE too, if you exceed the personal allowance.
However, if you also earn income from savings and investments held outside an ISA, a business, a second home, or another source, then it is likely that you will need to file a tax return. The same is true if you are self-employed.
In recent years, more people have found themselves being dragged into the self-assessment net thanks to the effects of fiscal drag. This is because inflation has been high, but tax thresholds have remained frozen. As a result, the tax-free allowances are worth less than they once were in real terms.
Some allowances have even been cut, including the dividend and capital gains allowances. This means investors can wrack up less in tax-free income and gains before a tax bill is due.
A common reason for falling foul of the taxman is simply not knowing that tax was due – so it is worth familiarising yourself with the rules. We take a closer look at who is eligible in our guide on how to file a tax return.
HMRC’s online tool also helps you check.
When is the self-assessment deadline?
In the UK, there are two self-assessment tax return deadlines:
- Deadline for paper tax returns: 31 October
- Deadline for online tax returns: 31 January
If you miss the paper deadline, you can file online instead. The forms must reach HMRC by midnight on the deadline date. Any tax owed also has to be paid to HMRC by 31 January.
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