Removing Onerous Obstacles in the Tax code for Mainstreet Businesses Act or the ROOT for Mainstreet Businesses Act This bill amends the Internal Revenue Code to modify the tax treatment of personal holding companies. The bill excludes from the definition of "personal holding company" a corporation with greater than 50% stock ownership held by nonresident alien individuals with no effectively connected income under tax provisions regarding expatriation to avoid tax or the taxation of nonresident alien individuals. The bill also excludes from personal holding company income certain rents and royalties that are derived in the active conduct of a trade or business and are not received from a related person.