Do I have to continue filing U.S. tax returns if I retire abroad?

If you are a U.S. citizen or a resident alien, the rules for filing income, estate and gift tax returns and paying estimated tax are generally the same, whether you are in the United States or abroad. With taxation of worldwide income, your U.S. and foreign income is subject to U.S. income tax, regardless of where you reside. It is a citizenship-based income tax.

Elsewhere in the world, the basic rule is that taxes are based on residency and not on taxation of worldwide income based on citizenship.