As a U.S. citizen or U.S. green card holder, you remain liable to tax in the United States of America (U.S.).
In many cases, you may even have to file two tax returns: A “Federal” and a “State” tax return. The obligation to declare does not stop if you are going to live and/or work outside the US. TCO offers, in cooperation with Solutions 4 Expats BV (Constanze Woelfle CPA), the possibility to have these declaration(s) taken care of for you.