I used to live in chicago .there are lot of students went to a 會計事務所(ower is a chinese CPA).spent $50.she will help you file the tax form. all RA ,TA don not pay tax.she used a treaty .sorry I forget the number. so many years. so many students went to there .nothing wrong happened.Tell you the truth.untill today I don not know if it is legal or illegal.but this 會計事務所 is famouse in chicago area. I haven't heard it involved in any trouble,every year there are still lot of students and H-1b go to there ,ask for professional tax help.