Snowbird US Substantial Presence Calculator
How many days can you spend in the US before triggering US tax residency? Includes the closer-connection exception window (Form 8840) and treaty tiebreaker triggers (Form 8833).
Day counter
SPT is technically met, but you can escape US tax residency by filing Form 8840 (Closer Connection Exception) with the IRS by June 15 of the following year.
| Current year days | 150 |
| Prior year days (×1/3) | 40.00 |
| Two-prior year days (×1/6) | 16.67 |
| Weighted total | 206.67 |
The weighted day formula
Under IRC §7701(b)(3), the substantial presence test weights three years of US presence:
- Current calendar year days × 1
- Prior calendar year days × 1/3
- Two-prior calendar year days × 1/6
The test is met if the weighted total is at least 183 AND the current-year days are at least 31. Days where you were in the US under specific exemptions (foreign-government related, certain student/teacher visas, days you were prevented from leaving due to a medical condition) do not count.
Form 8840: the snowbird escape valve
The Closer Connection Exception (CCE) is a statutory exemption from US tax residency for individuals who meet the SPT but maintain a 'closer connection' to a foreign country. Indicators include: primary residence, family, vehicle registration, driver's licence, banking, social and religious organisations, voting registration. Form 8840 is the procedural mechanism — it must be filed by June 15 of the following year and is statutorily unavailable when current-year US days are 183 or more.
The 183-day trap
A Canadian who spends 183 days or more in the US in a single calendar year cannot use Form 8840 regardless of other ties. The only remaining avenue is the Article IV treaty tiebreaker: filing Form 8833 attached to Form 1040-NR, asserting residence in Canada by treaty. This is materially more complex and audit-prone than Form 8840 — strongly recommend a cross-border accountant.
Year-end planning
Many snowbirds calibrate their winter trip to land below 120-130 current-year days, keeping a safety margin against unexpected return-trip days. The calculator above shows your maximum additional days for the current year.
Related decisions
If you ultimately move to the US permanently, see the Departure Tax Calculator for Canadian-side consequences. If you are a US citizen already, see the US Citizens in Canada Calculator — SPT is moot for citizens (you are always a US tax resident regardless of days).