Small Business/Self-Employed Topics. Sole Proprietorships. A sole proprietor is someone who owns an unincorporated business by himself or herself. However, if you are the sole member of a domestic limited liability company (LLC), you are not a sole proprietor if you elect to treat the LLC as a corporation. If you are a sole proprietor use the information in the chart below to help you determine some of the forms that you may be required to file.