What is a sole proprietor? Upsolve August 19, 2018 19:05 A sole proprietor is someone who owns an unincorporated business by himself or herself. See definition here: https://www.irs.gov/businesses/small-businesses-self-employed/sole-proprietorships. Related articles I'm stuck in the income-expense loop. Can you help? Can I file for bankruptcy after moving to a new state? Why you should not include credit card or personal loan debt payments in Schedule J (Expenses) How do I find the value of my motor vehicle if it's not listed in KBB? The different ways to be self-employed Comments 0 comments Article is closed for comments.