Substantial presence test calculator.

The rule, variable by variable

The IRS treats an alien as a U.S. resident for tax purposes if they meet either the green card test or the substantial presence test for a calendar year. For the substantial presence test you need both parts: presence on at least 31 days during the current year, and 183 days over a three-year window counted this way:

• every day present in the current year, times 1;
• days present in the first year before, times 1/3;
• days present in the second year before, times 1/6.

You are treated as present on any day you are physically in the United States at any time during the day, so a short evening stopover counts unless an exception applies. This tool keeps exact fractions and compares whole sixths, so a result like 182.83 is never rounded up to 183.

Days that do not count

Publication 519 says not to count: days you commute to work in the U.S. from a residence in Canada or Mexico if you regularly commute; days under 24 hours spent in transit between two places outside the U.S.; days as a regular crew member of a foreign vessel; days you could not leave because of a medical condition that arose while you were here; days under a NATO visa as a member of a force or civilian component; and days as an exempt individual. Exempt individuals include certain foreign government-related individuals, teachers and trainees, students, and professional athletes at a qualifying charitable sports event. Students on F, J, M or Q visas are generally not exempt after more than five calendar years of exempt student, teacher or trainee status, unless they show they do not intend to reside permanently and substantially complied with their visa. Enter only the days left after these exclusions.

Worked examples

The IRS example. 120 days in each of 2025, 2024 and 2023 gives 120 + 40 + 20 = 180. Under 183, so not a resident under this test for 2025.

Hypothetical, passes the weighted test. 150 days in 2025, 180 in 2024, 90 in 2023 gives 150 + 60 + 15 = 225, so the test is met. Because the person was here fewer than 183 days in 2025, a closer connection claim is worth examining (see below).

Hypothetical, fails the 31-day floor. 30 days in 2025 with 365 in each earlier year gives 30 + 121.67 + 60.83 = 212.5 weighted days, but 30 is below 31, so the test is not met.

The closer connection exception and Form 8840

Even if you meet the test, you may be treated as a nonresident if you were here fewer than 183 days during the year, kept a tax home in a foreign country, and had a closer connection to that country than to the United States. You claim it by attaching a completed Form 8840 to your tax return by the Form 1040-NR due date. If you do not file on time you cannot claim it. Exempt individuals and people claiming the medical-condition exclusion file Form 8843 instead.

Common mistakes

• Counting days of exempt status or Canada and Mexico commuting.
• Forgetting the 31-day floor when prior years are heavy.
• Using a fiscal year. The test runs on the calendar year.
• Assuming the test applies to green card holders. They are residents under a separate test.
• Treating the result as a visa or immigration-status answer. It is a tax test.

What this does not cover

It does not run the green card test, treaty tie-breaker rules, dual-status years, the first-year choice, or any state residency test, and it does not decide whether your closer connection claim is strong. It is built for individuals with simple day counts and is not tax advice.

Sources

• IRS: Substantial presence test — 31 days, 183 weighted days, excluded days, example (page reviewed March 14, 2026).
• IRS: Publication 519, U.S. Tax Guide for Aliens (2025) — Days of presence, exempt individuals, closer connection, Form 8840 and 8843.
• IRS: About Form 8840 — Closer connection exception statement (page reviewed March 30, 2026).

Retrieved October 2026. Publication 519 is revised each year for that year's returns.