Chapter 06 · Topic 06.2 · Substantial Presence Test
Substantial Presence Test: the 183-day formula
The SPT (IRC §7701(b)) determines whether a Canadian becomes a US tax resident without changing immigration status. Formula 100 % year N + 1/3 year N-1 + 1/6 year N-2. Threshold 183 weighted days + 31 days minimum in the current year.
Direct answer · 60-second summary
The 60-second version
The SPT (Substantial Presence Test, IRC §7701(b)(3)) is the tax test that determines if a Canadian becomes a U.S. tax resident without changing immigration status. Formula: if the sum of days of presence in the US over 3 years (current year + 1/3 of year N-1 + 1/6 of year N-2) reaches 183 days AND at least 31 days are in the current year, you are a tax resident for the current year.
- Current year: 100 % of days.
- Year N-1: 1/3 of days.
- Year N-2: 1/6 of days.
- Commute days Canada → US (work) are not counted.
- If SPT met but < 183 days in the current year: Closer Connection Exception (Form 8840) remains available.
Acronyms used in this guide
- IRS — Internal Revenue Service
- SPT — Substantial Presence Test (IRC §7701(b))
- IRC — Internal Revenue Code
- ARC — Agence du revenu du Canada
- CRA — Canada Revenue Agency
- I-94 — Arrival/Departure record kept by CBP for nonimmigrants
The SPT formula in detail
IRS weighs days by recency:
| Year | Weighting | Example: 120 US days |
|---|---|---|
| Current year (N) | 1 day = 1 day | 120 days counted |
| Year N-1 | 1 day = 1/3 day | 40 days counted |
| Year N-2 | 1 day = 1/6 day | 20 days counted |
| Total weighted | 180 days |
Cumulative conditions to trigger SPT:
- Total weighted ≥ 183 days.
- At least 31 days in the current year.
If either condition fails, no SPT, hence non-resident for the year.
Practical cases for Canadian snowbirds
For many snowbirds with a stable pattern:
Case 1: 4 months US each year (≈ 122 days)
Weighted total: 122 + 122/3 + 122/6 = 122 + 40.67 + 20.33 = exactly 183 days. SPT triggered. Fortunately, 122 < 183 in the current year, so Form 8840 Closer Connection available.
Case 2: 5 months US each year (≈ 152 days)
Weighted total: 152 + 50.67 + 25.33 = 228 days. SPT triggered. 152 < 183 in current year, Form 8840 still available.
Case 3: 6 months US (180 days)
Weighted total: 180 + 60 + 30 = 270 days. SPT triggered. 180 < 183 in current year (slim margin), Form 8840 available. Watch for going over.
Case 4: 184 days in current year
Form 8840 unavailable ("< 183 days" condition fails). Becomes US tax resident for that year — worldwide US filing required, unless treaty tie-breaker (Article IV Canada-US) decides for Canada.
Which days count and which don't
Any day of physical presence in the US counts (even a few hours). But exceptions apply:
Days that DO NOT count
- Commute days: Canadian or Mexican living in CA/MX who "regularly commutes" to work in the US — those days are excluded.
- Transit days < 24 h en route to another country.
- Foreign transport crew days.
- "Medical condition" days when prevented from leaving.
- Exempt individuals: diplomatic staff, J-1 teachers (limited), F-1 students (5 years), amateur athletes competing.
Important: air transit
A 6-hour layover in Atlanta en route to Punta Cana generally doesn't count if documented as transit. But a trip beginning AND ending in the US, or including a US overnight, counts.
Tax consequences of becoming US resident
If SPT met and no Closer Connection nor Tie-Breaker:
- Worldwide reporting: all worldwide income on Form 1040.
- FBAR (FinCEN 114): report foreign accounts > $10K USD.
- Form 8938: report foreign financial assets (variable thresholds).
- Foreign tax credit via Form 1116 or Form 2555 (foreign earned income exclusion).
- Spouse / children: residency does not transfer automatically.
- Canadian filing: if still Canadian tax resident, full T1 also — double-tax risk before credit.
Three options if SPT met
- Closer Connection Exception (Form 8840) — available if < 183 days in current year AND tax home in Canada AND closer ties to Canada. See Form 8840 guide.
- Treaty Tie-Breaker (Article IV Canada-US treaty) — available even if > 183 days in current year. Filing Form 8833 + Form 1040-NR. See tie-breaker guide.
- Accept US tax residency — Form 1040 worldwide + FTC. Evaluate with cross-border tax advisor.
Calculate your days yourself
Simple worksheet:
| Year | US days | Weighting | Weighted days |
|---|---|---|---|
| 2026 (current) | ? | ×1 | ? |
| 2025 | ? | ×1/3 | ? |
| 2024 | ? | ×1/6 | ? |
| TOTAL | ? | ||
See also the Days-of-Presence Calculator.
Common mistakes
- Confusing 183 weighted days with 183 days in the current year — two distinct thresholds.
- Forgetting arrival/departure days — both count as US days.
- Thinking that exiting Canada (not US) resets the count — no, US days remain counted on calendar.
- Filing Form 8840 late — deadline June 15 for CCE (extends to October 15 with Form 4868).
- Assuming tax residency = immigration residency — two distinct regimes.
Official forms mentioned (direct links)
Links to the latest known version of each form as of the last review date. Verify you are using the current version before any filing — it is your responsibility. CanadaFlorida.com is not responsible for your use of these links.
- Form 8840 — Closer Connection Exception Statement (IRS). https://www.irs.gov/forms-pubs/about-form-8840
- Form 1040-NR — U.S. Nonresident Alien Income Tax Return. https://www.irs.gov/forms-pubs/about-form-1040-nr
- Form 8833 — Treaty-Based Return Position Disclosure. https://www.irs.gov/forms-pubs/about-form-8833
- FinCEN Form 114 (FBAR). https://bsaefiling.fincen.treas.gov/main.html
- Form 8938 — Statement of Specified Foreign Financial Assets. https://www.irs.gov/forms-pubs/about-form-8938
- IRS Publication 519 — U.S. Tax Guide for Aliens. https://www.irs.gov/publications/p519
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.
- IRS — Substantial Presence Test. irs.gov/spt
- IRS — Closer Connection Exception. irs.gov/closer-connection
- IRS Publication 519 — U.S. Tax Guide for Aliens. irs.gov/p519
- IRC §7701(b)(3) — Cornell LII. cornell.edu/§7701
- Convention fiscale Canada-US, Article IV (résidence). canada.ca/treaty-us
Logical next step
Form 8840 is the main defense for a snowbird who crosses the weighted threshold.
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.