Despite more than 57,815 taxpayers filing their 2024/25 UK tax return on 6 April 2025 – the first day they were able to do so - many people leave their returns to the last minute, or beyond. Here are the deadlines you need to know to help you plan ahead and avoid penalties.

Do you need to complete a Self Assessment tax return?

Most people who are employed pay tax through Pay As You Earn (PAYE), so are not automatically required to file a tax return. The exception for PAYE taxpayers who earned more than £150,000has been abolished for 2024/25. However, if you’re self-employed, a partner in a partnership business, a trustee or the executor of an estate, you’ll pay tax through Self Assessment and you’re therefore required to complete a Self Assessment tax return. 

You may also need to complete a tax return if you have any other untaxed income, such as money from renting out a property, tips and commission, income from savings, investments and dividends or foreign income. It’s sometimes permissible to pay tax on non-employment income through your PAYE code but when it exceeds certain limits you’ll be required to pay tax through Self Assessment.

When do you need to pay your tax liability?

If you’re in Self Assessment, you’re liable to pay the balance of your tax liability by the 31 January following the end of the tax year. In subsequent tax years, you’ll generally be liable to make two interim payments on account either side of the end of the tax year. These payments are calculated by taking the previous year’s income tax liability and splitting this across two payments. The first payment must be paid by 31 January in the relevant tax year and the second by the following 31 July.

You’re required to pay your liability by 31 January following the end of the tax year regardless of whether your tax return was finalised on paper or online.

Penalties for late payment

The penalties for late payment increase depending on the delay of payment by the taxpayer:

• 30 days late – 5% of the tax liability 

• Five months after first penalty – additional 5% of tax outstanding

• 11 months after first penalty – additional 5% of tax outstanding

Late payment penalties must be paid within 30 days of the date the notice assessing the penalty is issued, otherwise interest will be charged on the penalty at the official rate, currently at 8.5%. 

When is the deadline to file your tax return?

You should submit your tax return for the year by the 31 January (31 October for paper tax returns) following the end of the tax year, finalising your tax liability from which the two interim payments will be deducted. 

If your liability has increased in comparison to the previous year, there will be a balancing payment due. On the other hand, if your liability has fallen in comparison to the previous year, then you will have paid too much and a repayment will be due from HMRC. It’s important to note that if you know well in advance that your taxable income is going to decrease, then you may reduce your interim payments on account, improving your cashflow over the year.

Penalties for late filing

Like with late payment, failure to file your tax return by the deadline is penalised with a graduated scale of penalties:

• One day late - £100 

• Three months late - daily £10 penalties for up to 90 days

• Six months late – 5% of the tax liability or £300, whichever is greater

• 12 months late – additional 5% of liability or £300, whichever is greater

Even if you have no tax liability for the year, if you file your tax return late you could be liable for £1,600 in late filing penalties alone.

What should you do?

Filing your tax return can be a stressful experience, and that’s why we are here to help. For a handy summary of the tax rates, allowances, and deadlines.

For help with interpreting the figures to complete your tax return, advice on tax planning, or if you’ve previously been issued penalties, get in touch and we’ll guide you through the entire process. We’ll ensure that you’re set up to make the right payments at the right time, every time.