Many business owners are running their business on a schedule C.   If you are single member LLC or an Unincorporated Business with one owner. You report your income and expenses on a Schedule C.   It is the simplest form of business.  People who self employed part time use a Schedule C although they are employed full time.   Most Door Dashers, Grub hubers, directors of boards, consultants, doctors, plumbers, electricians and much more utilize Schedule Cs for their selfemployed income and expenses.