The term expatriate has 2 meanings: It can refer to someone who has decided to live in another country. It can also refer to someone that has decided to renounce previous citizenship as well. For US citizens, regarldess of where they live, they must declare all worldwide income and are subject to US taxes. If however, a US citizen renounces their citizenship and offically expatriates, they are free of this tax burdon. For many who plant multiple flags, this is the ultimate goal. It is worth noting that in order to offically expaptriate, one must already have a second passport.