Procupine, I think I shall stop here. First thing, I have no idea what papers employers send to IRS. My only guess is they dont send anything, they just report Tax Withholdings. Since I don't have much legal expertise, I'd rather say, if you have too much concerns then its better to get some professional consultation OR pay those taxes as you always did in the past. But I still think there shouldn't be any problem, because many students (above 90%) work off campus saying the are US citizens when they are on F1, then later they move to H1. When that haven't matter then .... it should be okay. Otherwise, the obvious question is: How someone became H1 from citizen? Just my thought.