A self-assessment tax return (2019/2020) is a bleak affair. The good news is you can keep your tax to a minimum (and TAXO'D the taxman) by knowing your Allowable Expenses, Tax Reliefs & Refunds.
A self-assessment is a horrid affair which becomes more difficult (and costly) the later you leave it. Avoid these costly and common mistakes (and TAXO'D the taxman) when filing your tax return
If you work as a freelancer / self-employed (and are not already using TAXO'D). Then you will need to submit a Self-Assessment Tax Return to HMRC which is done online or by post via the SA100 form.
If you need to inform HMRC about less common types of income, a deduction or even tax relief then you will need to complete the SA101 form in addition to your main SA100 Self Assessment tax return form
If you need to inform HMRC more about your employment income then you will need to complete the SA102 form in addition to your main SA100 Self Assessment tax return
If you need to inform HMRC about any income from self-employment then you will need to complete either the SA103S or the SA103F form in addition to your main SA100 Self Assessment tax return.
If you need to inform HMRC about any income from renting out property in the UK then you will need to complete the SA105 form in addition to your main SA100 Self Assessment tax return.
If you need to inform HMRC about any income from foreign sources then you will need to complete the SA106 form in addition to your main SA100 Self Assessment tax return.
If you need to inform HMRC about any tax you may own from capital gains then you will need to complete the SA108 form in addition to your main SA100 Self Assessment tax return.
Thinking about working for yourself? Then you will need an understanding of the taxes you will pay to HMRC. Here is the TAXO'D basic guide to: Understanding Income Tax for Freelancers and the Self Employed.