Who must file U.S. taxes as an expat

The United States is one of only two countries on Earth that taxes its citizens on their worldwide income regardless of where they live (the other is Eritrea). If you hold a U.S. passport or a green card, the IRS considers you a U.S. taxpayer — even if you haven't set foot in the country in a decade, even if you owe nothing, even if your bank, employer, and apartment are all on the other side of the world.

This article answers the first question every American abroad eventually asks: do I actually have to file?

The short answer

If your worldwide income for the year exceeds the standard filing threshold for your status, you must file a U.S. federal tax return (Form 1040) — no matter where you live, no matter whether you owe tax after foreign-tax credits or exclusions, no matter whether you also file a return in your country of residence.

Filing thresholds for tax year 2025 (filed in 2026)

The IRS sets gross-income thresholds each year. If you're under the threshold for your status, you generally don't have to file. For tax year 2025, the rough numbers are:

Two things on this table catch expats off-guard:

• Married filing separately is effectively $5. If your spouse is a non-U.S. person and you don't elect to treat them as a resident, your filing threshold is functionally zero.
• Self-employment income kicks in at $400. If you make more than $400 freelancing, contracting, or running a one-person business abroad, you must file — even if your total income is well under the single-filer threshold.

"But I already pay tax in my country"

It doesn't matter. The U.S. filing requirement is based on citizenship and income, not on whether tax is owed. Most Americans abroad legitimately end up owing $0 to the IRS after applying either the Foreign Earned Income Exclusion (Form 2555) or the Foreign Tax Credit (Form 1116) — but they still have to file the return to claim those benefits.

Reports that go beyond the 1040

For expats, the income-tax return is often the easy part. The traps are the information reports:

• FBAR (FinCEN Form 114). If the combined balance of all your foreign financial accounts ever exceeded $10,000 USD on any day of the year, you must file an FBAR by April 15 (auto-extended to October 15). Penalties for willful non-filing start at $10,000 per account, per year. See What is FBAR?
• Form 8938 (FATCA). Higher thresholds than FBAR — for an expat filing single, you generally need to file if foreign financial assets exceeded $200,000 on the last day of the year or $300,000 at any point. Filed with your 1040.
• Form 8621. If you own a foreign mutual fund or ETF, you almost certainly own a PFIC, and you almost certainly need to file this form. The tax treatment is brutal.
• Form 5471 / 8865. Required if you own shares of a foreign corporation or interest in a foreign partnership. Penalties for missing this form start at $10,000 — and they apply even if your ownership is tiny.

Green-card holders abroad

Holding a green card means you are a U.S. tax resident, period. Living outside the U.S. doesn't change that. Until you formally abandon the green card (Form I-407) or it expires and is not renewed, the IRS treats you exactly like a U.S. citizen for tax purposes — worldwide income, FBAR, FATCA, the whole stack.

What if you haven't filed in years?

You are not alone, and you are not without options. The IRS has a program called the Streamlined Foreign Offshore Procedures specifically designed for Americans abroad who fell out of compliance non-willfully. It lets you file the last three years of returns and six years of FBARs, with no penalties on the FBARs and no failure-to-file or failure-to-pay penalties on the returns — provided you meet the eligibility criteria and submit a truthful non-willfulness statement.

This is genuinely the best deal the IRS offers. If you've been ignoring U.S. taxes for years, do not just "start filing this year" and hope for the best — that is called a quiet disclosure and it is the worst-case strategy. Read the Streamlined article, and consider talking to an EA or CPA who has run dozens of these.

The simple decision tree

1. Are you a U.S. citizen or green-card holder? If no, this article does not apply to you. If yes, continue.
2. Did your worldwide income exceed the threshold for your status? If yes, you must file Form 1040. If no, you may still want to file (to claim refundable credits or to start the statute of limitations running).
3. Did your foreign accounts ever exceed $10,000 combined? If yes, file FBAR.
4. Did your foreign financial assets exceed the FATCA thresholds? If yes, file Form 8938 with your 1040.
5. Do you own foreign mutual funds, a foreign company, or a foreign partnership? Get professional help. Forms 8621, 5471, and 8865 are not DIY territory.

Next steps

• If you're a salaried employee abroad: read the FEIE and FEIE vs. Foreign Tax Credit.
• If you have foreign bank accounts: read What is FBAR?
• If you haven't filed in years: read Streamlined filing procedures.