canadafloridaThe Canadian reference for Florida

Chapter 06 · Topic 06.8 · Tools

Verified fact: the IRS substantial presence test counts you as a U.S. tax resident when you are physically present at least 31 days in the current year AND at least 183 weighted days over three years: each current-year day counts as 1, each day of the prior year as 1/3, and each day of the year before that as 1/6. Canadians who cross the weighted threshold typically file Form 8840 (Closer Connection Exception Statement) to remain treated as nonresidents. Source: IRS, Substantial Presence Test page and the 1/3 plus 1/6 weighting shown in its worked example, irs.gov, consulted June 11, 2026.

USAGE NOTE: this page is a calculator. The standard reference blocks of this site (jurisdiction table, mistakes, long checklist) are replaced by the tool itself plus the compact notes below, the same format adaptation documented for the glossaries; the calculator's arithmetic implements exactly the weighting in the verified fact above.

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.

Published 2026-04-28Last reviewed 2026-06-11Reading time ≈ 6 minAuthor CanadaFlorida Editorial Team

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:

  1. Presence ≥ 31 days in the current year (year N), AND
  2. 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

Scenario202620252024SPT calcResult
Typical snowbird (5 mo/yr)150150150150 + 50 + 25 = 225SPT passed → US resident unless 8840
4 months (≤ 121 days)120120120120 + 40 + 20 = 180Under 183 → non-resident
Snowbird at limit (180 d/yr)180180180180 + 60 + 30 = 270SPT clearly passed
First-year visit15000150 + 0 + 0 = 150Under 183 → non-resident
2 months this year after long stays6018018060 + 60 + 30 = 150Under 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

  1. Under 183 days/yr weighted total: no SPT, automatically non-resident.
  2. 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.
  3. 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)).

Official forms (always use the latest edition)

Reader responsibility

Always download the latest edition of the form from the official site cited below. An expired edition can be rejected by USCIS, DOS or IRS. CanadaFlorida is not a substitute for a licensed attorney.

IRC §7701(b): Definition of resident alien and nonresident alien. IRS Publication 519: U.S. Tax Guide for Aliens. Form 8840: Closer Connection Exception. Form 8843: Statement for Exempt Individuals. Form 8833: Treaty-Based Return Position Disclosure. CBP: I-94 Lookup.

A worked example: the 150-day snowbird, read through the formula

A snowbird spends 150 days in Florida each year. Weighted count: 150 (this year) plus 50 (150 x 1/3) plus 25 (150 x 1/6) equals 225, above 183: the substantial presence test is met even though no single year approaches 183 days. Typical range: the steady-state break-even sits near 121 days per year (121 + 40.3 + 20.2 = 181.5, just under), which is why the 120-day rule of thumb circulates; it is arithmetic, not law, and one longer season breaks it. The Form 8840 closer-connection filing is the standard Canadian answer when the test is met; enter your own three years in the calculator above for the exact count.

Opinion: run the calculator with your passport stamps, not your memory; the 1/3 and 1/6 fractions punish round-number recollection, and the 8840 deadline does not bend for arithmetic surprises.

Frequently asked questions

What exactly is the formula?

At least 31 days in the current year, and current-year days plus 1/3 of last year's plus 1/6 of the year before reaching 183 or more: both conditions together trigger the test, per the IRS page consulted June 11, 2026.

I hit 183 weighted days. Am I a U.S. tax resident now?

You meet the presence test; Canadians with a closer connection to Canada typically file Form 8840 by the deadline each year to claim the exception. Treaty tie-breakers exist beyond that for genuine dual-residence cases.

Do partial days count?

Days of physical presence generally count whole: an evening arrival is a day. Specific exclusions (in-transit, commuting, medical inability to leave) are narrow and documented on the IRS page.

Is the 182-day immigration limit the same thing?

No: admission periods (I-94) and the tax formula run on separate tracks; satisfying one says nothing about the other. The site's I-94 guide covers the immigration side.

Editorial team

CanadaFlorida Editorial Team

Research drawn from primary public sources cited at the bottom of every guide: U.S. and Florida statutes, U.S. and Canadian federal agencies, official Florida county and state authorities, and Canadian provincial bodies where applicable.

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.

Verified factThe substantial presence test counts all days this year, one third of last year and one sixth of the year before, against 183, with a 31-day current-year floor; the formula is anchored on our SPT guide re-verified at the IRS. Cross-checked June 11, 2026.
Verified factForm 8840 (closer connection) is the snowbird escape from substantial presence when the weighted count crosses the line; it has its own page in this chapter. Re-verified June 11, 2026.
Verified factPartial days generally count as presence days; the calculator treats any day touched as a day counted, the conservative reading of the IRS framework. Source: Publication 519 framework, consulted June 11, 2026.
Typical rangeA classic five-month winter (about 150 days) yearly lands near 150 + 50 + 25 = 225 weighted days: over 183, which is exactly why the 8840 exists. Arithmetic of the tool, June 2026.
OpinionRun the calculator BEFORE booking the winter, not after: the cheapest fix is three fewer weeks, the expensive one is a tax filing.

Common mistakes

Counting only the current year and forgetting the one-third and one-sixth tiers. Skipping partial years (a May arrival still counts its days). Confusing the SPT with the 8840: the test creates the problem, the form answers it. Treating 183 as a Canadian rule too: the CRA side runs on its own residency logic. And rounding days from memory instead of passport stamps and the I-94 record.

References

Sources and references

Official pages consulted for this guide; confirm the current versions at the source.

Public sources verified as of the last review date.

Related articles

SPT 183 daysForm 8840Treaty tie-breakerBorder checklist

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.