When must I pay income tax?

Hi. I started helping people in gardens doing gardening jobs 4 years ago. It was very still in the beginning doing about 8 jobs a month and just surviving. I now have more clients and want to know if I must register a company and what about the previous years of earning something. Must I pay a penalty.

The tax threshold is currently R73,650 per year which means you don't pay tax below this amount.