It is a big one. Many expats had to resign their US citizenship to avoid this silly law.<p>Double taxation only exists in Aethopia and the US.<p>Read this blog: <a href="http:&#x2F;&#x2F;www.overseas-exile.com&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.overseas-exile.com&#x2F;</a><p>Protection? Yes, maybe that&#x27;s the reason. To support the US military efforts and budget.<p>On a side-note: If I would applied to the US greencard, and then decided to move back to Germany, I would have to pay double income taxes. To Germany and to the US. You don&#x27;t even need to be US citizen.