from a tax savings point of view it is a good move.  But, in my opinion, giving up his U.S citizenship is not right. Every person should pay their "fair share" of income tax.  There are many ways to legally minimize your taxes without giving up U.S. citizenship.  He should have consulted a CPA tax expert and a good financial planner. If he ever comes back to the U.S. he will have to pay taxes. He will have to pay taxes in the country he moves to, although it may be a lower rate.