Who Is Considered a Resident Alien in the US?

For federal tax purposes, a person is considered a resident alien in the US if they are not a U.S. citizen but meet one of three tests under 26 U.S.C. §7701(b): they hold a green card, they pass the substantial presence day-count test, or they make a valid first-year election.¹ The label matters because a resident alien is taxed on worldwide income the same way a U.S. citizen is, while a nonresident alien is generally taxed only on U.S.-source income.²

Green Card Holders

The simplest path is the green card test. If USCIS has issued you a Permanent Resident Card (Form I-551) and that status was in effect on any day of the calendar year, you are a resident alien for tax purposes for the entire year.³ It makes no difference whether you actually lived in the United States during that time.

Green card status for tax purposes does not quietly expire when you leave the country or your card lapses. It continues until one of three things happens: you voluntarily surrender the card and formally abandon your immigrant status, USCIS administratively revokes it, or a federal court orders it revoked.⁴ Long-term green card holders who give up their status may also face expatriation tax rules.

The Substantial Presence Test

You can also become a resident alien purely by spending enough time in the country. The substantial presence test has two parts. You must be physically present in the U.S. for at least 31 days during the current year, and your weighted day count across the current year and the two prior years must reach 183.⁵

Each day in the current year counts as a full day.
Each day in the first preceding year counts as one-third of a day.
Each day in the second preceding year counts as one-sixth of a day.

The weighting matters. Someone in the U.S. 120 days a year for three straight years counts 120 + 40 + 20 = 180 days and does not pass. At 125 days a year, the count becomes 125 + 42 + 21 = 188, and they do.

Days That Don’t Count: Exempt Individuals

Certain visa holders can exclude their U.S. days from the calculation entirely. These exempt individuals include foreign government personnel on A or G visas (except A-3 and G-5), teachers and trainees on J or Q visas, students on F, J, M, or Q visas, professional athletes present for a charitable sports event, and people who intended to leave but could not because of a medical condition that arose while they were in the country.⁵

The exemptions for teachers and students are time-limited. A teacher or trainee cannot exclude days if they were already exempt as a teacher, trainee, or student for any part of 2 of the previous 6 calendar years. A student’s exemption runs out after any part of more than 5 calendar years, unless they can show they do not intend to reside permanently in the U.S.⁶

To claim the exemption you must file Form 8843, either with your tax return or on its own if you owe no return. Miss it, and the IRS can count every day you were here.⁶

The Closer Connection Exception

Even if you meet the substantial presence test, you can escape resident classification if you were in the U.S. fewer than 183 actual days during the current year, kept your tax home in a foreign country all year, had closer ties to that country than to the U.S., and did not apply for or take steps toward a green card.⁷

The IRS decides where your closer connection lies by looking at concrete facts: where your permanent home is, where your family lives, where you keep personal belongings, where you vote, where you hold a driver’s license, and which charities you support.⁷ You claim the exception by filing Form 8840 by the due date of your return, including extensions. File it late and you lose the exception.⁸

Treaty Tie-Breakers

A tax treaty between the U.S. and your home country can also override resident status. Many treaties contain tie-breaker rules that assign residency to one country when both would otherwise claim you, looking in turn at your permanent home, center of vital interests, habitual abode, and nationality. If the treaty puts you in the other country, you can file as a nonresident for U.S. purposes, but you must attach Form 8833 to disclose the position. Disclosure is mandatory when the treaty-based income exceeds $100,000, and each failure carries a $1,000 penalty.⁹

The First-Year Election

The third path is one people opt into. If you arrive partway through the year and do not yet meet the substantial presence test, you can elect to be treated as a resident alien for the portion of the year you were in the U.S. You must have been physically present for at least 31 consecutive days during the year and for at least 75% of the days from the start of that 31-day period through year-end. Up to 5 days of absence still count as days of presence for the 75% calculation.¹⁰

Why volunteer for worldwide taxation? The election opens doors that are otherwise closed: filing jointly with a U.S. citizen or resident spouse, claiming certain credits, and taking the standard deduction that dual-status filers cannot use. The cost is reporting global income for the resident portion of the year.

What Changes Once You’re a Resident Alien

Resident aliens file Form 1040 and are taxed on income from anywhere in the world: a U.S. paycheck, a foreign rental, overseas investments, all of it. The same deductions, credits, and filing statuses that citizens use are available.¹¹

Wages earned while working in the U.S. are subject to Social Security and Medicare tax at the standard 6.2% and 1.45% rates. Students and trainees on F-1, J-1, M-1, or Q-1 visas who were previously exempt from FICA lose that exemption once they become resident aliens. A totalization agreement between the U.S. and your home country may keep you on the foreign social security system instead.¹²

If you’re a resident alien married to a nonresident, both spouses can elect under IRC §6013(g) to treat the nonresident spouse as a resident and file jointly. The joint election gives you the married-filing-jointly standard deduction ($32,200 for 2026) and wider brackets, but it also pulls your spouse’s worldwide income into the U.S. tax base for the full year. Once made, the election stays in force until formally terminated.¹³¹⁴

Foreign Account and Asset Reporting

Resident classification also switches on foreign-asset reporting rules. If your foreign financial accounts together exceeded $10,000 at any point in the year, you have to file FinCEN Form 114, the FBAR, with the Financial Crimes Enforcement Network. The threshold is aggregate across accounts.¹⁵

Form 8938, filed with your return under FATCA, is a separate obligation with different thresholds. For a resident alien living in the U.S., the filing thresholds are:¹⁶

Single or married filing separately: more than $50,000 on the last day of the year, or more than $75,000 at any point.
Married filing jointly: more than $100,000 on the last day of the year, or more than $150,000 at any point.

The initial penalty for missing Form 8938 is $10,000, with additional $10,000 penalties accruing every 30 days after IRS notice, up to $50,000 more.¹⁷ The FBAR and Form 8938 are not substitutes; many people have to file both.

Dual-Status Years and When Residency Ends

The year you arrive in or leave the U.S. is often a dual-status year, treated as nonresident for part of it and resident for the rest. During the nonresident portion, only U.S.-source income is taxable; during the resident portion, worldwide income is.¹⁸

Dual-status filers cannot take the standard deduction. That’s $16,100 (single) or $32,200 (married filing jointly) for 2026 that has to be replaced by itemizing.¹⁴ The first-year election exists partly to get around this outcome by making you a full-year resident.

How residency ends depends on how it started. For a green card holder, the termination date is the first day you are no longer a lawful permanent resident, provided your tax home was in a foreign country and you kept a closer connection to that country for the rest of the year. For someone who qualified through substantial presence, the termination date is the last day of physical presence in the U.S. during the year, again with the foreign tax home and closer connection requirements. A de minimis rule allows up to 10 days of U.S. presence after your intended departure without resetting the date.¹⁹

If you were a resident this year and will also be a resident for any part of next year, there is no early termination: you’re treated as a resident through December 31.¹⁹ Early termination is only available when you’re leaving U.S. residency for good.

1
Office of the Law Revision Counsel. 26 U.S. Code 7701 – Definitions
2
Internal Revenue Service. Publication 519 (2025), U.S. Tax Guide for Aliens
3
Internal Revenue Service. U.S. Tax Residency – Green Card Test
4
Internal Revenue Service. Residency Starting and Ending Dates
5
Internal Revenue Service. Substantial Presence Test
6
Internal Revenue Service. Form 8843 – Statement for Exempt Individuals and Individuals With a Medical Condition
7
Internal Revenue Service. Closer Connection Exception to the Substantial Presence Test
8
Internal Revenue Service. Form 8840 – Closer Connection Exception Statement for Aliens
9
Internal Revenue Service. Claiming Tax Treaty Benefits
10
Internal Revenue Service. Tax Residency Status – First-Year Choice
11
Internal Revenue Service. Alien Taxation – Certain Essential Concepts
12
Internal Revenue Service. Aliens Employed in the U.S. – Social Security Taxes
13
Internal Revenue Service. Nonresident Aliens
14
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
15
Financial Crimes Enforcement Network. BSA Electronic Filing Requirements for Report of Foreign Bank and Financial Accounts (FinCEN Form 114)
16
Internal Revenue Service. Do I Need to File Form 8938, Statement of Specified Foreign Financial Assets
17
eCFR. 26 CFR 1.6038D-8 – Penalties for Failure to Disclose
18
Internal Revenue Service. Taxation of Dual-Status Individuals
19
eCFR. 26 CFR 301.7701(b)-4 – Residency Time Periods