Most people in the UK pay all their tax ‘at source’, for example, through Pay As You Earn (PAYE) if they are employed, and are not required to file a tax return. 

So self assessment does not affect everyone and you will normally only need to complete a form if one or more of the following apply to you: 

          •    You are working for yourself – you are self-employed; 

          •    You are a partner in a partnership business; 

          •    You are a company director, except for directors of not-for-profit organisations who receive no pay; 

          •    You are a minister of religion – any faith or denomination; 

          •    You are a trustee or the executor of an estate. 

You also might need to complete a self assessment tax return if: 

          •    You have untaxed income. This could be, for example, interest that is not taxed before it is paid to you or rental income. If you are an employee or a pensioner and the income is less than £2,500 a year you might not have to complete a tax return. But if you receive other untaxed income and the tax due on it cannot be collected via your PAYE coding notice you will need to complete a tax return; 

          •    You receive regular annual income from a trust or settlement, or you receive income from the estate of a deceased person and further tax is due;•You have taxable foreign income whether or not you are resident in the UK. This includes non-UK resident landlords. You can find out more on the GOV.UK website; 

          •    You have income from savings and investments of £10,000 or more before tax; 

          •    You or your partner receive child benefit and your income is over £50,000. This is because of the high income child benefit charge; 

          •    You have capital gains where: 

                    >    You have given away or sold assets worth £45,200 or more for 2017/18; or 

                    >    You have a capital loss but your gains net of any losses are more than the annual exemption for 2017/18 of £11,300; or 

                    >    You have no losses to claim but your gains are more than the annual exemption for 2017/18 of £11,300. 

HMRC may also want you to complete a return for other reasons. 

Note that if HMRC have sent you a tax return or a notice to complete one, then you must fill it in and return it by the due date unless there is a good reason you do not need to be in self assessment and HMRC agree to cancel it.