Answer: With an EAD, you can join any company or business, including having your own company. But you should not work for yourself full-time, because you may have potential problems with USCIS about the question of your ability to pay the salary, and meeting other requirements of AC-21 portability. If you work for your won business in part-time and you also have a full-time job, then it should not be a problem. (http://www.greencardapply.com/question/question08/question08_0604.htm)