Snowbird SPT + Form 8840: The 183-Day Survival Guide

Canadians who spend extended time in the United States — particularly retirees wintering in Florida, Arizona, or California — face the risk of being classified as US tax residents under the Substantial Presence Test. Understanding the formula, the Form 8840 exemption, and how to manage your day count is the foundation of snowbird tax planning.

The weighted day formula

The Substantial Presence Test (SPT) looks at your US presence over three consecutive calendar years using a weighted formula. You are treated as a US resident for the current year if:

• Days in the current year: count at 1/1 (full value)
• Days in the first preceding year: count at 1/3
• Days in the second preceding year: count at 1/6

If the sum of those weighted days equals or exceeds 183, you pass the SPT and are treated as a US resident alien for tax purposes — meaning you must file a 1040, report worldwide income, and comply with all US resident tax rules.

Example. You spent 120 days in the US in 2024, 100 days in 2023, and 90 days in 2022. Calculation: 120 + (100 / 3) + (90 / 6) = 120 + 33.3 + 15 = 168.3 days. You are below 183 — SPT not met. Now increase 2024 to 140 days: 140 + 33.3 + 15 = 188.3 — SPT met.

The 183 current-year absolute limit. In addition to the weighted formula, if you are physically present in the US for 183 days or more in the current calendar year alone, you meet the SPT regardless of prior-year counts. The weighted test is the more commonly triggered one for snowbirds who carefully manage their days.

Form 8840 mechanics and deadline

If you meet the SPT but have a closer connection to Canada (or another country), you can claim the Closer Connection Exception by filing Form 8840, “Closer Connection Exception Statement for Aliens.” This form is your primary protection as a snowbird.

The closer connection test. You must demonstrate that:

1. You were present in the US fewer than 183 days during the current year (the Form 8840 exception is only available if current-year days are below 183 — see the next section).
2. You had a tax home in Canada (or another country) during the year.
3. During the year, you had a closer connection to Canada than to the US.

Closer connection factors include: where your permanent home is; where your family lives; where your social, cultural, and professional ties are; the country of your driver’s licence and car registration; where you vote; where your bank accounts, investments, and professional licences are located; and which country you would identify as your home if asked.

Filing the form. Form 8840 is filed with the IRS by the due date of your US return (June 15 for individuals outside the US, or April 15 plus extensions). You do not need to file a full 1040 to file Form 8840 — non-residents without US-source income only need to file 8840 to claim the exception. The form asks for your days in the US in each of the three test years and your tax home details.

Important: no Form 8840 if current-year days are 183 or more. The Closer Connection Exception is not available if you spent 183 or more days in the US in the current year. At 183+ current-year days, your only option is the Canada-US tax treaty tiebreaker under Article IV — which requires filing Form 8833 with a 1040-NR.

What if you cross 183 current-year days

If you discover that you have been in the US for 183 or more days in the current calendar year, the Form 8840 door closes. Your options are:

Treaty tiebreaker. File a 1040-NR with Form 8833 attached, claiming non-resident status under Article IV of the Canada-US Tax Treaty. The tiebreaker hierarchy determines residency: permanent home, then centre of vital interests, then habitual abode, then citizenship. Most Canadian snowbirds with strong Canadian ties — home, pension, healthcare, social network — will prevail under the permanent home or centre of vital interests tests. See the Canada-US Treaty Article IV guide for the full hierarchy.

Pay US tax. If treaty relief is unavailable or impractical, you may owe US tax on worldwide income as a resident alien. A foreign tax credit for Canadian taxes paid would offset double taxation in most cases, but the administrative burden of a full US resident return is significant.

Days that do not count (exempt categories)

Certain days in the US do not count toward the SPT:

• Days commuting from Canada. If you regularly commute from a residence in Canada to work in the US, those commuting days are excluded.
• Days in transit. Days spent in the US in transit between two foreign locations — passing through a US airport between Canada and Mexico, for example — do not count.
• Days due to medical condition. If a medical condition arose while you were in the US and prevented you from leaving, those days are excluded. This exemption requires contemporaneous documentation: physician letters and evidence that departure was medically impossible.
• Exempt individuals. Foreign government officials, teachers, trainees, and students on certain visa categories are exempt from the SPT entirely, but this category does not apply to typical Canadian snowbirds on B-2 visitor visas.

Note that “partial days” in the US count as full days. Arriving on the morning of January 1 and leaving late on the same day counts as one day.

Year-end planning

Day count log. Keep a contemporaneous log — a diary, phone location history, boarding passes, credit card records — documenting your travel dates. In an audit, the IRS bears the burden of showing SPT is met; you bear the burden of showing Form 8840’s requirements are met. A contemporaneous log is the most persuasive evidence.

The 120-day rule of thumb. Most cross-border planners advise keeping US days under 120 in any calendar year. At 120 days: weighted calculation is 120 + (up to 120/3) + (up to 120/6) = 120 + 40 + 20 = 180 — just under the 183 threshold, with a small cushion for any prior years where you exceeded 120 days. Reducing to 119 days adds additional buffer.

State income tax. The SPT and Form 8840 address federal US residency. Some states have their own residency tests. Florida and Nevada have no income tax; Arizona and California do. Spending more than 9 months in California triggers California resident status regardless of the SPT result.

Use our calculator to track your SPT day count and see how close you are to the threshold.

Snowbird Substantial Presence Calculator