Health insurance glossary
Substantial presence test (US)
Plain-English definition
The substantial presence test is the US Internal Revenue Service rule for deciding whether someone who is not a US citizen is treated as a US resident for tax purposes. It is met with at least 31 days in the US in the current year and at least 183 days over three years, counting all current-year days, one third of last year's and one sixth of the year before.
By the HealthRate editorial desk
Where this applies: US federal tax rule. For your own situation, ask a tax professional.
How it works
Example from the IRS: 120 days in each of three years counts as 120 + 40 + 20 = 180 days, which falls short of 183 (IRS).
Someone who meets the test can still be treated as a non-resident if they were in the US for fewer than 183 days in the year, kept a tax home in another country and had a closer connection to it. This is claimed on IRS Form 8840 (IRS).
Some days do not count, for example certain transit days of under 24 hours.
Why it matters
Snowbirds who spend long winters in the US can meet the test without realizing it. It is a tax rule, not a health insurance rule, but it often comes up when planning how long to stay.