I am a PhD student in the US, originally from Germany and here on a F-1 visa.
Mid last year, my status changed from being on a fellowship to being on a research assistantship. Hence, I got a 1042-S and a W-2. I have been using the tax treaty so far and would like to continue declaring taxes for my US income in Germany.
However, the tax return generated with the GLACIER Tax Prep (formerly CINTAX) software says that the tax treaty can only be applied to the fellowship (1042-S):
Is this true? If not, what information could I have entered that made it think that the tax treaty does not apply?