If i become a citizen of Costa Rica do i have to pay the US taxes if i work there?

I assume you are not asking if you will literally have to pay US taxes (which depends on how much you make in CR), but more so if you can be subject to taxation by the US (even if you become a CR citizen). It doesn't matter what other country you receive citizenship in. The US does not formally recognize citizenship from other countries. What matters is whether you renounce your US citizenship. As long as you are a US citizen, your income (outside of the amount of income abroad that you can exclude each year) is taxable. So the short answer is YES, you can be taxed. As to whether you will have a tax bill depends on how much you make. Based on the wages in CR, you don't anything to worry about. Read this: http://www.irs.gov/publications/p54/index.html EDIT: Contrary to what the next asnwer says, you are NOT subject to taxation by the US government on your Costa Rican wages if you renounce your US citizenship. That's like asking a Tico who works in a supermarket in CR to pay US income taxes. That's ridiculous.