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).
Frequently asked questions
What is the US Substantial Presence Test (SPT)?
IRC §7701(b)(3) deems you a US tax resident if you spent at least 31 days in the US during the current calendar year AND your weighted day count (current year + 1/3 of prior year + 1/6 of two-prior year) is at least 183 days. Being a US tax resident means you must file Form 1040 on your worldwide income, not just US-source income.
What is Form 8840 and when do I file it?
Form 8840 (Closer Connection Exception) is filed by an individual who would otherwise be a US resident under the SPT, but who maintains a closer connection to a foreign country (i.e., Canada). It establishes that even though you met the SPT, you remain a non-resident for US tax purposes. The form is due by June 15 of the year following the relevant tax year. It can only be filed if your current-year days in the US are below 183 — otherwise the closer-connection exception is statutorily unavailable.
What if I spent more than 183 days in the US in one year?
If your current-year US days are 183 or more, Form 8840 is no longer available. Your only avenue to claim Canadian residency is the treaty tiebreaker under Article IV of the Canada-US Tax Treaty, filed on Form 8833 attached to a Form 1040-NR. This is a more complex filing that asserts your residence is Canada despite physical presence. A cross-border tax accountant is strongly recommended in this scenario.