Helping with your self-assessments: what do we need from you? The online self-assessment form can be very straightforward to use - if your business income and expenditure are simple, for example, if your income doesn't exceed your personal allowance. in Public bookmarkswith self_assessment Note: The online self-assessment form can be very straightforward to use - if your business income and expenditure are simple, for example, if your income doesn't exceed your personal allowance.