Two numbers decide the test: at least 31 days in the US this year, and at least 183 over three years, weighting last year at a third and the year before at a sixth.
Meeting both makes a person a US resident for tax purposes, with a Form 1040 to file, unless a route below changes that. Pick your case.
Some of my days in the US may not count
Fits if some days were regular commutes to work from Canada or Mexico, transits under 24 hours between two places outside the US, days as crew of a foreign vessel, or days a medical condition that arose in the US kept you there.
Publication 519 lists six kinds of day that do not count, and the IRS test page five: the extra kind is the NATO visa item. Publication 519 says a business meeting, even one at the airport, means you are not in transit.
The IRS text (Publication 519, then the test page)
“Do not count the following as days of presence in the United States for the substantial presence test. Days you commute to work in the United States from a residence in Canada or Mexico if you regularly commute from Canada or Mexico. Days you are in the United States for less than 24 hours when you are in transit between two places outside the United States. Days you are in the United States as a crew member of a foreign vessel. Days you are unable to leave the United States because of a medical condition that arose while you are in the United States. Days you are in the United States under a NATO visa as a member of a force or civilian component to NATO. However, this exception does not apply to an immediate family member who is present in the United States under a NATO visa. A dependent family member must count every day of presence for purposes of the substantial presence test. Days you are an exempt individual.”
“However, there are exceptions to this rule. Do not count the following as days of presence in the U.S. for the substantial presence test: Days you commute to work in the U.S. from a residence in Canada or Mexico if you regularly commute from Canada or Mexico. Days you are in the U.S. for less than 24 hours, when you are in transit between two places outside the United States. Days you are in the U.S. as a crew member of a foreign vessel. Days you are unable to leave the U.S. because of a medical condition that develops while you are in the United States. Days you are an exempt individual (see below).”
I met the count but stayed under 183 days this year
For a year under 183 days in the US. The IRS also requires a tax home abroad all year, a closer connection to that country, no green card step that year or before, and Form 8840 filed on time.
This exception can treat someone who met the test as a nonresident. Publication 519's tax home is the main place of business, employment or post of duty, wherever the family home is.
The IRS text (the exception page and the Form 8840 instructions)
“Even if you met the substantial presence test, you can still be treated as a nonresident of the United States for U.S. tax purposes, within Internal Revenue Code Section 7701(b)(1)(B), if you: Were present in the United States less than 183 days during the year, and Had a closer connection during the year to one foreign country in which you had a tax home than to the United States (unless you had a closer connection to two foreign countries, discussed next), and Maintained a tax home in that foreign country during the entire year (see Chapter 28 of Publication 17 for a discussion of the tax home concept), and Had not taken steps toward, and did not have an application pending for, lawful permanent resident status (green card).”
“Note: You are not eligible for the closer connection exception if any of the following apply. • You were present in the United States 183 days or more in calendar year 2025. • You are a lawful permanent resident of the United States (that is, you are a green card holder). • You have applied for, or taken other affirmative steps to apply for, a green card; or have an application pending to change your status to that of a lawful permanent resident of the United States.”
Another country also treats me as its tax resident
Fits if you are a resident of another country under its own law and its tax treaty with the US has a tie-breaker rule.
Where a treaty has a tie-breaker rule, Publication 519 treats a person it makes resident abroad as a nonresident for US income tax, and a US resident for other purposes. In certain instances that treatment can trigger the section 877A expatriation tax.
The IRS text (Publication 519)
“Dual residents. The rules given here to determine if you are a U.S. resident do not override tax treaty definitions of residency. If you are a dual-resident taxpayer, you can still claim the benefits under an income tax treaty. A dual-resident taxpayer is one who is a resident of both the United States and another country under each country’s tax laws. The income tax treaty between the two countries must contain a provision that provides for resolution of conflicting claims of residence (tiebreaker rule). If you are treated as a resident of a foreign country under a tax treaty, you are treated as a nonresident alien in figuring your U.S. income tax. For purposes other than figuring your tax, you will be treated as a U.S. resident.”
“Note: In certain instances when an individual is treated as a nonresident alien pursuant to a tiebreaker rule in a relevant tax treaty, it can trigger section 877A expatriation tax.”
Two different 183s: the weighted 183 over three years belongs to the test, and 183 days in the current year alone closes the closer connection exception.
Which return and which due dates apply to a year?
That depends on whether a year is resident or nonresident, which the test, its exceptions and a treaty all bear on. A year can also be both, on the IRS residency page: “You can be both a nonresident and a resident for U.S. tax purposes during the same tax year. This usually occurs in the year you arrive or depart from the United States. If so, you need to file a dual-status income tax return.” When residency ends, on the IRS residency dates page: “In general, if you meet the substantial presence test, your residency ending date is your last day of presence in the United States followed by a period during which: You are not present in the United States, You have a closer connection to a foreign country than to the United States, and You are not a resident of the United States during the calendar year following that of your last day of presence in the United States. Under the general rule, the residency ending date is December 31 of the calendar year in which you left the United States.” The IRS dual-status page routes such a year by where it ends: Form 1040 for someone who is a resident on its last day, and Form 1040-NR for someone who is not. For a resident, Publication 519: “Resident aliens should file Form 1040 or 1040-SR at the address shown in the Instructions for Form 1040. The due date for filing your return and paying any tax due is April 15 of the year following the year for which you are filing a return (but see the Tip, earlier).” For a nonresident it prints two dates: “If you are an employee and you receive wages subject to U.S. income tax withholding, you will generally file by the 15th day of the 4th month after your tax year ends. For the 2025 calendar year, file your return by April 15, 2026. If you are not an employee who receives wages subject to U.S. income tax withholding, you must file by the 15th day of the 6th month after your tax year ends. For the 2025 calendar year, file your return by June 15, 2026.” The IRS nonresident taxation page, stamped 17 February 2026, words the April branch wider: “If you are an employee and you receive wages subject to U.S. income tax withholding, or you have an office or place of business in the United States, you must generally file by the 15th day of the 4th month after your tax year ends. For a person filing using a calendar year this is generally April 15.” This page resolves nothing between the two texts. A dual resident claiming treaty benefits, in Publication 519: “If you are a dual-resident taxpayer and you claim treaty benefits, you must file a return using Form 1040-NR with Form 8833 attached, and compute your tax as a nonresident alien.” On extensions: “For the 2025 calendar year, this will extend the due date to October 15, 2026. If your regular due date is June 15, 2026, this will extend the due date to December 15, 2026. You must file the extension by the regular due date of your return.” On paying: “Caution: An automatic 6-month extension to file does not extend the time to pay your tax. If you do not pay your tax by the original due date of your return, you will owe interest on the unpaid tax and may owe penalties. See Form 4868.” On weekends: “Tip: If the due date for filing falls on a Saturday, Sunday, or legal holiday, the due date is the next day that is not a Saturday, Sunday, or legal holiday.” Whether any of the dates above moved in 2026 was not checked for this page.
Does a US LLC filing Form 5472 make its owner a US resident?
The filing belongs to the company. Publication 519: “If a foreign person wholly owns a domestic DE, the domestic DE is treated as a domestic corporation separate from its owner (the foreign person) for the limited purposes of the requirements under section 6038A that apply to 25% foreign‐owned domestic corporations. The foreign-owned domestic DE must file a pro forma Form 1120 with Form 5472 attached by the due date (including extensions) of the return. The only information required to be completed on Form 1120 is the name and address of the foreign-owned domestic DE and items B and E in the first part.” And: “Also note that because the domestic DE is generally a transparent entity, the foreign person will include (or continue to include) on Form 1040-NR any of the domestic DE’s tax items that are subject to reporting.” The owner’s own status follows the two tests, in the same publication: “If you are an alien (not a U.S. citizen), you are considered a nonresident alien unless you meet one of the two tests described under Resident Aliens below.” A business can also mean a personal return: “Nonresident aliens who are required to file an income tax return should use Form 1040-NR. If you are any of the following, you must file a return. A nonresident alien individual engaged or considered to be engaged in a trade or business in the United States during 2025. (But see Exceptions, later.) You must file even if: Your income did not come from a trade or business conducted in the United States, You have no income from U.S. sources, or Your income is exempt from income tax.”
What closes the closer connection exception?
The IRS names six immigration forms on its closer connection page: “If you filed any of the following forms during or before the year in question, this indicates your intent to become a Lawful Permanent Resident of the United States and that you are not eligible for the Closer Connection Exception. Form I-508, Waiver of Rights, Privileges, Exemptions and Immunities Form I-485, Application to Register Permanent Residence or Adjust Status Form I-130, Petition for Alien Relative Form I-140, Immigrant Petition for Alien Worker Form ETA-750, Application for Alien Employment Certification Form OF-230, Application for Immigrant Visa and Alien Registration” So a form filed in a year closes the exception for that year and every later year. A green card holder is a resident under the other test, on the IRS green card test page: “You are a resident, for U.S. federal tax purposes, if you are a lawful permanent resident of the United States at any time during the calendar year. This is known as the "green card" test.” The tax home the exception needs, in Publication 519: “Your tax home is the general area of your main place of business, employment, or post of duty, regardless of where you maintain your family home. Your tax home is the place where you permanently or indefinitely work as an employee or a self-employed individual. If you do not have a regular or main place of business because of the nature of your work, then your tax home is the place where you regularly live. If you do not fit either of these categories, you are considered an itinerant and your tax home is wherever you work. For determining whether you have a closer connection to a foreign country, your tax home must also be in existence for the entire current year and must be located in the same foreign country to which you are claiming to have a closer connection.” Filing late costs the exception, in the 2025 Form 8840 instructions: “If you do not timely file Form 8840, you will not be eligible to claim the closer connection exception and may be treated as a U.S. resident. You will not be penalized if you can show by clear and convincing evidence that you took reasonable actions to become aware of the filing requirements and significant steps to comply with those requirements.” This page does not cover a closer connection to two foreign countries.
Who is an exempt individual, and who files Form 8843?
The IRS test page: “Do not count days for which you are an exempt individual. The term "exempt individual" does not refer to someone exempt from U.S. tax, but to anyone in the following categories: An individual temporarily present in the U.S. as a foreign government-related individual under an ‘A’ or ‘G’ visa, other than individuals holding ‘A-3’ or ‘G-5’ class visas. A teacher or trainee temporarily present in the U.S. under a "J" or "Q" visa, who substantially complies with the requirements of the visa. A student temporarily present in the U.S. under an "F," "J," "M," or "Q" visa, who substantially complies with the requirements of the visa. A professional athlete temporarily in the U.S. to compete in a charitable sports event.” For students, the IRS student page sets a year limit: “You will not be an exempt individual as a student if you have been exempt as a teacher, trainee, student, Exchange Visitor, or Cultural Exchange Visitor on an "F, " "J, " "M, " or "Q " visa for any part of more than 5 calendar years, unless you establish to the satisfaction of the IRS that you do not intend to reside permanently in the United States, and you have substantially complied with the requirements of your nonimmigrant status.” It defines compliance: “You are considered to have substantially complied with the visa requirements if you have not engaged in activities that are prohibited by U.S. immigration laws and could result in the loss of your nonimmigrant status.” Who files Form 8843 is where the IRS texts differ. The 2025 instructions: “If you are an alien individual (other than a foreign government- related individual), you must file Form 8843 to explain the basis of your claim that you can exclude days of presence in the United States for purposes of the substantial presence test because you: • Were an exempt individual, or • Were unable to leave the United States because of a medical condition or medical problem.” The About Form 8843 page, stamped 29 April 2026: “If you are an alien individual, file Form 8843 to explain the basis of your claim that you can exclude days present in the United States for purposes of the substantial presence test because you: Were an exempt individual. Were unable to leave the United States because of a medical condition or medical problem.” This page resolves nothing between them. The due date and what lateness costs are the next answer.
What does filing Form 8843 late cost?
The IRS texts disagree. The IRS test page, stamped 14 March 2026: “If you do not timely file Form 8843, you cannot exclude the days you were present in the U.S. as an exempt individual or because of a medical condition that arose while you were in the U.S. This does not apply if you can show, by clear and convincing evidence that you took reasonable actions to become aware of the filing requirements and significant steps to comply with those requirements.” The 2025 Form 8843 instructions: “If you don’t file Form 8843 on time, you may not exclude the days you were present in the United States as a professional athlete or because of a medical condition or medical problem that arose while you were in the United States. Failure to exclude days of presence in the United States could result in your being considered a U.S. resident under the substantial presence test. You won’t be penalized if you can show by clear and convincing evidence that you took reasonable actions to become aware of the filing requirements and significant steps to comply with those requirements.” Publication 519, stamped 30 April 2026, sets the due date and the narrower scope: “You must file Form 8843 by the due date for filing Form 1040-NR. The due date for filing is discussed in chapter 7. If you are required to file Form 8843 and you do not timely file Form 8843, you cannot exclude the days you were present in the United States as a professional athlete or because of a medical condition that arose while you were in the United States. This does not apply if you can show by clear and convincing evidence that you took reasonable actions to become aware of the filing requirements and significant steps to comply with those requirements.” This page resolves nothing between them.
This guide reports what the authorities and institutions involved publish, quoted, with the date each source was read. It is not tax, legal or immigration advice. Published rules change, and an individual case can turn on facts no page can see.
