Only two nations in the world have citizenship-based taxation: the United States and Eritrea in northeastern Africa.
Citizenship-based taxation means that the payment of taxes is
determined by citizenship rather than residency or the source of income.
In other words, the foreign income earned by an American abroad is
taxed by the Internal Revenue Service even though it is also assessed by
the nation in which he lives. An American businessman living in Hong
Kong is legally required to render unto two Caesars even if he receives
'benefits' from only one. This amounts to a stiff financial and
paperwork penalty on Americans who dare to depart their native soil.