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What is self-assessment?

For millions of people in the UK, your income tax is worked out for you. It's automatically deducted from your salary before you get paid.

But many others have to file a self-assessment tax return. This is to work out what you owe to HM Revenue & Customs (HMRC) on your income and capital gains. You have to include all income in self-assessment, not just that which hasn't been taxed at source.

The next deadline for self-assessments is for the 2023/2024 tax year. It's at midnight on 31 January 2025. If you don't submit yours on time, you could be fined.

Here's our guide to help you find out if self-assessment applies to you and what you may need to do.

Do you need to do a self-assessment?

There are 3 factors that influence whether you need to do a self-assessment. These relate to:

  • Employment
  • Other income
  • Benefits


If you're on the payroll of the company where you work, the income tax you owe will be taken off your salary before you receive it. 

This is a system called PAYE (pay as you earn), which means you don't usually have to complete a self-assessment tax return.

But you will need to do a self-assessment if you're either of the following:

  • Self-employed as a sole trader and earning more than £1,000 per tax year
  • A partner in a business partnership

Other income

You may also need to do a self-assessment on other income including:

  • Rent received from property you own
  • Tips and commission
  • Income received from savings, investments and dividends
  • Any foreign income

You can check whether you need to do a self-assessment by using this tool on the Government’s website.


There are other reasons why you might need to fill in a self-assessment tax return.

If you receive child benefit, you'll need to submit a return if you (or your partner) have an income that’s more than £50,000. This is because you'll have to pay the high income child benefit charge.

Some people also choose to do a tax return so they can claim certain types of income tax relief.

Another reason to complete a self-assessment return might be to prove you're self-employed so you can claim things like tax-free childcare or maternity allowance.

If you're still not sure whether you need to send a tax return, contact the HMRC self-assessment helpline on 0300 200 3310 to check.

How do I get a certificate of interest?

If you need a certificate of interest (tax certificate) to complete your tax self-assessment, please send us a secure e-message in online banking or by using chat in the mobile banking app. 

The certification of interest confirms the total amount of credit interest paid into an account over the tax year.

Once we receive your request, we’ll post this to you within 7 working days.

When is the deadline?

Each self-assessment period covers a tax year beginning and ending in early April. 

The deadline for the 2023/2024 tax year is at midnight on 31 January 2025. All online self-assessments covering the period from 6 April 2023 to 5 April 2024 have to be submitted by then. 

If you miss the deadline, there's a £100 fixed penalty.

If there are more delays, you can be fined further. After 3 months, there are extra penalties of £10 per day and these can increase again after 6 months and 12 months.

HMRC also charges interest on any tax due that's not paid by the deadline of 31 January.

Find out how to register and file your self-assessment on the Government's website.

How can you pay HMRC?

As long as you submit your online return on time, any amount you owe in tax is calculated automatically as soon as you’ve completed your self-assessment. 

Once you’ve submitted it, it’s easy to pay your bill using online banking. It’s similar to paying utility bills. Keep in mind that if you're an HSBC customer you'll be able to send up to £25,000 when making mobile or online payments.

To pay online you’ll need to find the relevant bank details for HMRC so you can make the transfer.

The GOV.UK website also has information about other ways of paying such as by Direct Debit, at a bank or building society or by cheque.