The first thing you need to do if you are self-employed and not earning a regular monthly salary, is to register as a provisional taxpayer so that you pay tax twice a year and therefore spread the tax burden over the year.
As a self employed taxpayer you should keep a spreadsheet on a monthly basis of all your income and any business related expenses (eg. car, cell phone, computer costs, stationery, wages, etc) so you are always on top of your your tax affairs. You can then use this to calculate your taxable income and therefore calculate how much tax you will pay. When you complete your annual tax return, you would include your business income and expenditure under the "Local Income" section.
Use our Calculator below to estimate how much tax you will pay on your earnings. Under "did you make any other income" - indicate Yes, and then include your earnings (after expenses) under local business profit.