No Federal Tax

I'm pretty sure you don't need to pay Ferderal Tax if you are doing research or teaching at Universities and research institute. Actually, paying tax or not doesn't depend on your visa, it only depends where you are from and your job. I asked these questions to IRS and was told that we can use the exempt even after I filed I-485 (adjustment to permanent residence). IRS sent me some sample forms on how to claim the exempt. Actually, my wife got the tax back for two straight years without any problem, even after she had the green card. That was quite a big amount for us.

Please call or e-mail IRS directly, I'm sure they will give you the best help. I suggest you ask the questions through their website, then you can keep all the records in case somebody questions you tax forms.I also have the samples and all the communtion record with IRS, they are not useful for us anymore. We would be very happy to give out if it is really helpful to somebody.