It is not necessary but it has a lot of advantages. As a business you will be only taxed on the profits you make (Income - Expenses), but as an individual you will be taxed on the total income you makeI want to start an online course, but I don't know how GST works in this case. Is it mandatory that each purchase needs to be given a GST invoice, e.g., if I make a course on the Udemy platform?