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Who should submit a tax return?

Find out whether you should submit a tax return, what to do if HMRC sends you a tax return, and what to do if your circumstances change

In this article
Do I need to submit a tax return? Who needs to fill in a tax return? Will I be sent a tax return?
What to do if you receive a tax return Tax returns if your circumstances change Submit your 2018-19 tax return with Which?

Do I need to submit a tax return?

If you run your own business as a sole trader or partnership, you'll need to complete a self-assessment tax return every financial year. But entrepreneurs aren't the only people who are required to complete a self-assessment return. 

If you run a limited company, however, you'll need to file a company tax return.

In this guide, we list the circumstances that would require a self-assessment tax return to be filed - from those in certain jobs, to those receiving certain forms of income.

Who needs to fill in a tax return?

Specifically, you'll need to fill in a tax return if:

  • you're self-employed, a business partner, or director of a limited company
  • you're an employee or pensioner with an annual income of £100,000 or more
  • you have a pre-tax investment income of £10,000 or more
  • your income (or your partner's) was over £50,000 and one of you claimed Child Benefit
  • you have income from abroad that you need to pay tax on
  • you were a trustee of a trust or a registered pension scheme
  • you received a P800 form from HMRC saying you didn't pay enough tax last year - and you didn't pay what you owe through your tax code or with a voluntary payment
  • you're a 'name' at the Lloyd's of London insurance market
  • you're a minister of religion
  • you're a trustee or representative of someone who has died.

If any of these apply, the onus is on you to declare this income to HMRC, which will usually ask you to fill in a tax return.

Use the Which? online tax calculator: our easy-to-use and jargon-free tax calculator offers personalised tax tips, and you can submit the form directly to HMRC.

Will I be sent a tax return?

HMRC may send you a tax return. This will generally happen if:

  • you have untaxed income – from investment, land or property, or from overseas
  • you make capital gains above the annual exempt amount (£11,700 for 2018-19)
  • you were required to fill in a tax return last year
  • you're a pensioner over 65 who gets reduced age-related allowance, though you may be sent a special short version that requires fewer details.

But if you know you need to submit a self-assessment tax return, you should not rely on HMRC to contact you. It's your responsibility to make sure you declare taxable income each year.


What to do if you receive a tax return

Anyone who receives a self-assessment tax return from HMRC is legally obliged to complete and submit it, either by post or by filing a tax return online.

If you miss the deadline and submit a late tax return, you'll be liable to pay a penalty, and may have to pay interest and surcharges on any tax you owe. The deadline for paper tax returns is 31 October, while the deadline for online tax returns is 31 January. 

The fines for submitting a late tax return are outlined below.

Tax returns if your circumstances change

If your circumstances change and you receive new income during the tax year (for example, you start letting property or sell a large number of shares), you must let your tax office know by 5 October following the end of the tax year. It will then decide whether you need to complete a tax return.

If you used to send a tax return but don't need to any more (for instance, if you're no longer self-employed), contact HMRC to close your self-assessment account.

Submit your 2018-19 tax return with Which?

Get a head start on your 2018-19 tax return with the Which? tax calculator. Tot up your tax bill, get tips on where to save and submit your return direct to HMRC with Which?.