The following guidelines are reproduced from the government’s website:
You must send a tax return if, in the last tax year (6 April to 5 April), you were:
self-employed as a ‘sole trader’ and earned more than £1,000
a partner in a business partnership
You will not usually need to send a return if your only income is from your wages or pension. But you may need to send one if you have any other untaxed income, such as:
money from renting out a property
tips and commission
income from savings, investments and dividends
Other reasons for sending a return
You can choose to fill in a tax return to:
claim some Income Tax reliefs
prove you’re self-employed, for example to claim Tax-Free Childcare or Maternity Allowance
If your income (or your partner’s, if you have one) was over £50,000, you may need to send a return and pay the High Income Child Benefit Charge.
Unfortunately, this is just the tip of the iceberg. For example, you may have to submit a return if you have made significant capital gains in a tax year.
If you are at all uncertain if you do need to file, please call. There are significant penalties for failing to register and submit a return. The deadline to register for the tax year 2018-19 is imminent, 5 October 2019, and so action should not be delayed.
If your circumstances have only recently changed – during the current 2019-20 tax year – you have more time, but it is worth getting the registration process completed so you can start to plan for any tax payments that may fall due 2020 and beyond.