Where you work does not matter, it depends on where you reside. There is a higher threshold if you live overseas before you need to file. As a US citizen or resident you are required to report your income where ever you earn it. You may get credits if it is earned in a foreign country and you have paid tax already but you need to report it all. FATCA is not impacted by where you earn your money. As far as the penalty is concerned it is impacted by where you live and how you file either single or married.