It actually all depends on what you want to do. Opening an overseas is not illegal for Americans, you just have to declare it when you file your taxes. However,

It actually all depends on what you want to do. Opening an overseas is not illegal for Americans, you just have to declare it when you file your taxes. However, having a bank account out of the reach of creditors or others who may seek legal action against you is advisable for people in certain fields. You could be a doctor in a risky part of medicine where people will sue you at a drop of a hat. You would put your money into a Cook Island Trust and then no one can get access to it. You are not doing anything illegal, you have paid taxes on that money and the government knows about it. Someone who has gained money through crime or sinister methods could do the same thing, but instead an American judge would just throw them in jail until they returned the funds. You could also own a company that does the majority of its business overseas. If you need to move money from one part of the world to another, sometimes it is just easier to keep it in Panama or Singapore. When you move the money back into the US, you would have to pay taxes on it. However in all cases, if you have an overseas account with a lot of money in it, you must accept that you are willing to flee the US to keep it.