Snowbird Days Calculator (US Substantial Presence Test)
How long can you winter in the US before the IRS treats you as a US tax resident? Enter your days for the last three years and this tool runs the Substantial Presence Test — all of this year's days, plus one-third of last year's and one-sixth of the year before — and screens the Form 8840 Closer Connection Exception.
How your weighted total is built
Each year's days times its weight. Only the weighted total is compared with the 183-day line.
| Year | Days | Weight | Weighted |
|---|
How this is calculated
The two-part test
You meet the Substantial Presence Test only if both are true: you were present at least 31 days in the current year, and your weighted three-year total is at least 183 days. Both conditions are set by statute. Source: IRS — Substantial Presence Test.
The weighted-day formula
weighted = (this year × 1) + (last year × 1/3) + (year before × 1/6). That is why steady visits of ~120 days a year stay under the line (120 + 40 + 20 = 180) while ~122 days a year crosses it. Source: IRS — Substantial Presence Test.
What counts as a day
Any part of a day physically present in the US counts as a full day. Some days do not count — commuting from Canada for work, under-24-hour transit between two foreign points, days you could not leave due to a US medical condition, and days as an "exempt individual" (certain visa holders, who file Form 8843). Most Canadian snowbirds have no exempt category and count all days; this tool does not model excluded or exempt days, so subtract them from your entries yourself. Source: IRS — Substantial Presence Test.
Closer Connection Exception (Form 8840)
Even if you meet the test, you may be treated as a nonresident if you were present strictly fewer than 183 days this year, kept a tax home in a foreign country (Canada) all year, had a closer connection to that country than to the US, and took no steps toward a US green card. You must file Form 8840 on time to claim it, and it can cover a closer connection to at most two foreign countries. Sources: IRS — Closer Connection Exception, About Form 8840.
Treaty tie-breaker & Canadian residency
If you are a resident of both countries, the Canada-US treaty (Article IV) tie-breaker decides one treaty residence in sequence: permanent home, centre of vital interests, habitual abode, nationality, then competent-authority agreement. Your Canadian (CRA) residency is a separate, fact-based test resting on significant residential ties — a home in Canada, a spouse or partner, and dependants. This tool decides none of these. Sources: IRS Publication 597 (US-Canada Treaty), CRA Income Tax Folio S5-F1-C1.
What this doesn't do
It does not verify your dates, model excluded/exempt/medical days, assess your closer-connection facts, apply the treaty tie-breaker, handle first-year or dual-status elections, or determine Canadian residency. It is a day-count screen only — confirm with a cross-border tax professional.
Common questions
How many days can a Canadian snowbird spend in the US before becoming a US tax resident?
The IRS Substantial Presence Test counts all of your days this year, plus one-third of last year's days, plus one-sixth of the days from the year before. If that weighted total reaches 183 and you were in the US at least 31 days this year, you meet the test. Because of the weighting, spending roughly 120 days a year every year keeps a typical snowbird under the line (120 + 40 + 20 = 180), but 122+ steady days pushes past 183.
What is the Substantial Presence Test formula?
Weighted days = (days present this year x 1) + (days last year x 1/3) + (days the year before x 1/6). You meet the test if the weighted total is 183 or more AND you were present at least 31 days in the current year. Any part of a day physically in the US counts as a whole day.
What is the Closer Connection Exception (Form 8840)?
Even if you meet the Substantial Presence Test, you can be treated as a nonresident by filing IRS Form 8840 if you were present strictly fewer than 183 days this year, kept a tax home in Canada all year, had a closer connection to Canada than to the US, and took no steps toward a US green card. The form must be filed on time to claim the exception.
Does meeting the US test change my Canadian tax residency?
No. Canadian (CRA) residency is a separate, fact-based test that turns on significant residential ties — a home in Canada, a spouse or partner, and dependants. If you are a resident of both countries, the Canada-US tax treaty tie-breaker in Article IV decides a single treaty residence. This calculator only screens the US day-count test.