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 (before taking off anything you can claim tax relief on)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: some COVID-19 grant or support payments money from renting out a property tips and commission income from savings, investments and dividends foreign income.
Check if you need to send a tax return if you're not sure.
Other reasons for sending a return: You can choose to fill in a tax return to: i, claim some Income Tax reliefs. ii, prove you're self-employed, for example to claim Tax-Free Childcare or Maternity Allowance. iii, If you get Child Benefit and If your income (or your partner's) was over £50,000, you may need to send a return and pay the High Income Child Benefit Charge.