Rule guide
US substantial presence test: weighted day counting
The US substantial presence test generally combines at least 31 days in the current year with a weighted three-year total of 183 days: all current-year days, one-third of prior-year days and one-sixth of second-prior-year days. Excluded days and exceptions can change the result.
What the test does
The test is one federal tax-residence test for non-US citizens. It is not an immigration stay limit, and a visa expiry date does not establish how long someone was admitted.
Apply the weighting
Start with days physically present in the current calendar year, then add one-third of countable days from the previous year and one-sixth from the year before that. Keep the 31-day current-year condition separate from the weighted total.
- Review IRS categories for days that do not count.
- Check the closer-connection exception and treaty position where relevant.
- Keep evidence for each physical-presence date.
Fictional example
Example only: Alex has 120 countable days this year, 120 last year and 120 two years ago. The weighted arithmetic is 120 + 40 + 20 = 180, below the test total, but exclusions and other tax rules still need review.
Official record and rule sources
Check the authority.
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