Yes, you need to let your insurer know and buy the appropriate addiitonal insuarnce. Right now, your car is presumably insured for your personal use, not for use in regularly transporting other persons as part of your job. The use and risk profile of what you are doing with your car is very different, I would imagine, from what is disclosed on your insurance application; that discreptancy, and your failure to keep your insurer appraised as to the use you make of your car, could result in coverage being denied if you have an accident. You also want to make sure that the coverage you have will cover injuries to your clients if you are in an accident, so you do not have to personally pay their medical costs (or worse--for any disabilities or deaths) out of pocket.