In most cases, yes. The United States uses citizenship-based taxation, meaning citizens and green-card holders must report their worldwide income on Form 1040 regardless of where they live. Moving abroad does not end the obligation to file a US tax return.
Filing is generally required once gross income exceeds the standard deduction for a given filing status, which is $15,750 for single filers or $31,500 for married filing jointly. However, there is a notable quirk for expats married to non-resident aliens. If filing as married filing separately, the threshold drops to just $5 of gross income. Separately, anyone with $400 or more of net self-employment income must file, regardless of the standard-deduction threshold.
Taxpayers living outside the country receive an automatic two-month extension to June 15 to file, and further extensions are available. While filing is mandatory, owing tax is not. Filing a US expat tax return is usually how individuals claim benefits like the Foreign Earned Income Exclusion (which shields up to $130,000 of earned income) or the Foreign Tax Credit. These tools often reduce the actual US tax owed to zero. Many people who owe nothing still must file to claim these benefits.