Chapter 06 · Topic 06.8 · Tools
US day-presence calculator (3-year rolling SPT) for Canadian snowbirds
SPT formula (IRC §7701(b)(3)): N days×1 + N−1×⅓ + N−2×⅙ ≥ 183 AND ≥ 31 in current year = US tax resident. Target 122 d/yr = under 183. Form 8840 if 122-182. Treaty tie-breaker beyond.
Direct answer · 60-second summary
The 60-second version
The day-presence calculator in the US is the key tool to check whether you cross the IRS Substantial Presence Test (SPT) and risk becoming a US tax resident. Official formula (IRC §7701(b)(3), IRS Pub 519):
- If ≥ 31 days in the current year AND
- Current-year days × 1 + N−1 days × ⅓ + N−2 days × ⅙ ≥ 183
= you pass the SPT and are US tax resident by default. To remain non-resident, options: (a) stay ≤ 182 days/yr and file Form 8840 (Closer Connection), (b) file Treaty Tie-Breaker via Form 8833 + 1040-NR (Canada-US treaty Article IV). This article provides the formula, worked examples, and implications for Canadian snowbirds.
Acronyms used in this guide
- IRS — Internal Revenue Service
- IRC — Internal Revenue Code
- SPT — Substantial Presence Test (IRC §7701(b))
- LPR — Lawful Permanent Resident
- PR — Permanent Resident (green card holder)
- CBP — U.S. Customs and Border Protection
- I-94 — Arrival/Departure record kept by CBP for nonimmigrants
Official formula
Per IRC §7701(b)(3)(A):
SPT formula
You are US tax resident if:
- Presence ≥ 31 days in the current year (year N), AND
- Weighted total ≥ 183 days over 3 years:
- Year N days × 1
- Year N−1 days × ⅓
- Year N−2 days × ⅙
Important: any day, even partial, counts as a full day (except IRS transit exceptions).
Worked examples
| Scenario | 2026 | 2025 | 2024 | SPT calc | Result |
|---|---|---|---|---|---|
| Typical snowbird (5 mo/yr) | 150 | 150 | 150 | 150 + 50 + 25 = 225 | SPT passed → US resident unless 8840 |
| 4 months (≤ 121 days) | 120 | 120 | 120 | 120 + 40 + 20 = 180 | Under 183 → non-resident |
| Snowbird at limit (180 d/yr) | 180 | 180 | 180 | 180 + 60 + 30 = 270 | SPT clearly passed |
| First-year visit | 150 | 0 | 0 | 150 + 0 + 0 = 150 | Under 183 → non-resident |
| 2 months this year after long stays | 60 | 180 | 180 | 60 + 60 + 30 = 150 | Under 183 → non-resident (≥ 31 days, SPT applies) |
Days that do NOT count
IRC §7701(b)(3)(D) excludes some days:
- Day in transit through the US (< 24 hours between two foreign flights).
- Day you couldn't leave due to medical condition arising in the US (Form 8843 required).
- Commuter day from Canada/Mexico for regular work.
- Day as foreign ship/aircraft crew member.
- Day as exempt individual (diplomat, F-1/J-1 student under conditions).
For typical Canadian snowbirds: every FL day counts. No exemption.
Options to stay non-resident
- Under 183 days/yr weighted total: no SPT, automatically non-resident.
- Form 8840 (Closer Connection Exception): if present ≤ 182 days in current year AND closer ties to a foreign country (Canada). Filing deadline: June 15 of following year. See dedicated article.
- Treaty Tie-Breaker (Article IV Canada-US treaty) via Form 8833 + Form 1040-NR: possible even if SPT passed, based on center of vital interests. More complex. See dedicated article.
Recommendations for Canadian snowbirds
- Keep a precise day log of US days (I-94 entry/exit).
- Target 122 days/yr averaged over 3 years = SPT under 183 (122 × 1.5 = 183).
- If you want 150-180 days/yr: mandatory to file Form 8840 every year.
- Beyond 182 days in a year: 8840 unavailable, treaty tie-breaker required.
- Green card (LPR) or citizenship = US tax resident regardless of days (Green Card Test, IRC §7701(b)(1)(A)(i)).
Formulaires officiels (toujours utiliser la dernière édition)
Responsabilité du lecteur
Toujours télécharger la dernière édition du formulaire depuis le site officiel cité ci-dessous. Une édition expirée peut être rejetée par USCIS, DOS ou IRS. CanadaFlorida ne se substitue pas à un avocat licencié.
Every figure, rate, threshold, and deadline in this guide is drawn from a verifiable primary source listed at the bottom of the page. The article is updated whenever the underlying rules change, with a fresh review date stamped at the top.
Sources and references
Public sources verified as of the last review date.
- IRC §7701(b)(3) — Substantial presence test. cornell.edu/§7701
- IRS Publication 519 — U.S. Tax Guide for Aliens. irs.gov/pub519
- Form 8840 — Closer Connection Exception. irs.gov/8840
- Convention fiscale Canada-US — Article IV (résidence). canada.ca/tax-treaties
Disclaimer
This guide is for educational purpose only. Figures, rates, thresholds, timelines and rules are drawn from public sources at the date shown and may change.
For any concrete decision, consult a licensed US immigration attorney and a cross-border tax attorney.