Who it applies to
Anyone who is not a US citizen or green card holder and spends time in the United States. It is one of two ways the IRS can classify you as a resident alien for tax purposes (the other being the green card test). Certain visa categories, such as F, J, M and Q students and trainees classified as "exempt individuals," have special rules and may exclude some days from the count — this tool counts physical presence only and does not apply those visa-specific exemptions.
How the days are counted
The test uses a weighted total across three years: the current year, and the two years before it, with each earlier year counted at a fraction of its full value.
- Count all days present in the current year at full value (×1).
- Count all days present in the prior year at one third value (÷3).
- Count all days present in the year before that at one sixth value (÷6).
- Add the three weighted totals together — if the sum is 183 or more, and you were present at least 31 days in the current year, you meet the Substantial Presence Test for that year.
Worked example
Say you spent 130 days in the US in 2026, 120 days in 2025, and 120 days in 2024. The weighted total is 130 + (120 ÷ 3) + (120 ÷ 6) = 130 + 40 + 20 = 190. Since 190 is 183 or more, and you had more than 31 days of presence in 2026, you meet the Substantial Presence Test for 2026.
Common questions
What if I meet the 183-day weighted total but was in the US fewer than 31 days this year?
The test does not apply to you for that year regardless of the weighted total — both conditions (weighted total of 183+ and at least 31 days in the current year) must be met.
Do all my days in the US count, even short trips?
Generally yes, any day with physical presence in the US counts, including partial days, though specific exceptions exist for certain commuters, transit passengers, and exempt individuals that this tool does not model.
Is this the same as being a US citizen or green card holder?
No. The Substantial Presence Test is a separate, day-count-based path to being treated as a US tax resident for a given year — it has nothing to do with citizenship or green card status.
Does meeting the test mean I owe US tax on all my worldwide income?
Meeting the Substantial Presence Test generally means you are taxed as a US resident for that year, which does typically extend to worldwide income, subject to any applicable tax treaty. This is a general explanation, not tax advice for your specific situation.