The American tax system is unusual compared to almost every other country in that the US taxes based on citizenship rather than on residence. So while most countries only those people who live in that country, and/or those who have income arising in the country, the US taxes all US citizens (and green card holders) on their worldwide income, wherever in the world they live.
Top 3 Reasons US Expats Should Catch Up With Their IRS Tax Filing by Using the Streamlined Procedure
With FATCA and a raft of intergovernmental tax information exchange agreements allowing Uncle Sam to know more about expats' finances than ever before, a growing number of expats are choosing to become compliant by using the Streamlined Procedure IRS amnesty program.
Since it was introduced in 2014, nearly 50,000 US expats have used the Streamnlined Procedure to catch up with their US tax filing and so avoid IRS penalties. By claiming one or more of the exemptions available to expats, they most often end up owing no tax to the IRS, while they also gain something even more valuable: peace of mind.