I am postdoc in Boston (USA) doing research for the benefit of the public, and I'm from Germany.
I receive a normal salary from my university in Boston (not a stipend).
I'm on a J1 visa since July 2018.
Now for the tax report I need to decide if I want to use the German-US tax treaty.
If I use it, I will get the federal income tax back, as the online tax reporting tool (Windstar) tells me: https://trr.thomsonreuters.com/
Tax in Germany is generally higher for my case than US tax. But do I have to pay taxes at all if I use the tax treaty? Or do I have to pay later when I am back in Germany?
I don't know how long I will be here, but probably altogether around 3-5 years.