You cannot form a sole proprietorship with any other person, spouse or otherwise. By definition, a sole proprietorship can have only one owner. As soon as more than one owner gets involved, the entity would have to become a general partnership. However, you should speak to an attorney and an accountant about the wisdom (or not) of doing business in a form that leaves your personal assets open and vulnerable in the event of a lawsuit or judgment -- which is the case with sole proprietorships and general partnerships. There are forms of business entities, such as S corporations or limited liability companies, that may be able to provide you with the tax advantages you are seeking without exposing yourself to personal liability.