The Substantial Presence Test: How Many Days Can a Non-Resident LLC Owner Spend in the US Before Becoming a US Tax Resident?

The Visit That Quietly Turns You Into a US Taxpayer

You can own a US LLC for years without ever owing US federal income tax. But the moment you spend "too many" days physically inside the United States, the IRS can reclassify you from a non-resident alien (taxed only on US-source income) into a US tax resident (taxed on your worldwide income). The trigger has nothing to do with your LLC, your visa, or whether you have an EIN — it is a purely day-counting test called the Substantial Presence Test.

For founders who travel to the US for trade shows, supplier meetings, Amazon FBA inspections, or just long holidays, this is one of the most expensive mistakes you can make without realising it. Here is exactly how the rules work, where the real cut-off sits, and how to use Form 8840 to protect yourself.

The Substantial Presence Test — In Plain English

You become a US resident for tax purposes for the calendar year if you meet both of the following conditions, as published by the IRS:

You are physically present in the United States for at least 31 days during the current year, AND

You are physically present for at least 183 days over a 3-year window — current year + 2 prior years — using a weighted formula:

• Every day in the current year counts as 1 day.
• Every day in the prior year counts as 1/3 of a day.
• Every day in the year before that counts as 1/6 of a day.

The IRS gives the following example: if you were in the US 120 days each year in 2023, 2024 and 2025, then for 2025 you count 120 + (1/3 × 120) + (1/6 × 120) = 120 + 40 + 20 = 180 days. That is below 183, so you are NOT a US tax resident for 2025.

But push it to 122 days every year and you cross the line. The 183 figure is not "183 days this year" — it is a rolling, weighted total. This is the trap.

A Practical Rule of Thumb

If you spend roughly the same number of days in the US every year, the safe ceiling is about 121 days per year (121 × 1.5 = 181.5). Once you start averaging 122+ days year after year, you trip the substantial presence test and become a US resident by default — even if you never spent 183 days in any single year.

If your travel pattern is uneven, you have to do the actual math each year. Don't estimate.

Which Days Don't Count

The IRS explicitly allows you to exclude certain days from the count. The most relevant exclusions for non-resident founders:

Days you are physically in the US for less than 24 hours while in transit between two foreign destinations (a layover in Atlanta on the way from London to Mexico City does not count).

Days you regularly commute to work in the US from a residence in Canada or Mexico.

Days you are stuck in the US due to a medical condition that arose while you were already there.

Days you are an "exempt individual" — a category that mainly covers foreign government employees on A/G visas, teachers and trainees on J/Q visas, students on F/J/M/Q visas, and certain professional athletes. Most LLC owners on B-1/B-2 visitor visas do NOT qualify as exempt individuals.

Importantly, "exempt individual" does NOT mean "exempt from US tax." It is a specific category that lets you ignore those days when counting toward the 183. If you exclude any days, you must file Form 8843 with the IRS, even if you have no US tax return to file otherwise.

The Lifeline: The Closer Connection Exception (Form 8840)

Even if you tripped the substantial presence test, you can still be treated as a non-resident for the year — but only if you meet every one of these conditions for that year:

You were physically present in the US for fewer than 183 actual days during the year (the un-weighted, raw count).

You had a "tax home" in a foreign country for the entire year.

You had a closer connection to that foreign country than to the US (where your home, family, belongings, business activities outside your tax home, driver's licence, voting jurisdiction, and social/cultural ties are located).

You did NOT apply for, or take steps toward, US lawful permanent resident status (green card) during the year.

If all four are true, you file Form 8840 — the Closer Connection Exception Statement for Aliens — and you are treated as a non-resident even though the day-count math said otherwise.

There is one hard ceiling that nothing can override: if you spent 183 or more raw days in the US during the current year, the closer connection exception is unavailable. Period. At that point the only escape is a tax treaty tie-breaker rule, and that is a different, much more complex analysis.

The Filing You Must Not Forget

Form 8840 must be filed by the due date of your non-resident return (Form 1040-NR), including extensions. If you don't normally file a 1040-NR, you still send Form 8840 to the IRS service center on its own by that same deadline.

The IRS is explicit: if you fail to file Form 8840 on time, you cannot claim the closer connection exception unless you can show "by clear and convincing evidence" that you took reasonable steps to comply. That is a very high bar — and not a fight you want to pick. File the form on time, every year you might be close.

Why This Matters Even More When You Own a US LLC

Becoming a US tax resident does not just mean filing a 1040 — it changes your entire global tax picture:

Your foreign-owned single-member LLC (currently a "disregarded entity" for IRS purposes) suddenly belongs to a US tax resident. The protective treatment that limits US tax to US-source effectively connected income disappears. You become taxable on your worldwide income, including non-US salary, foreign rental income, foreign dividends, and crypto.

You are now in the FBAR / Form 8938 reporting regime for your foreign bank accounts. Failure-to-file penalties on FBAR alone can be severe.

If you take steps to become a green card holder, you also become disqualified from the closer connection exception going forward.

The wrong 30 days in Miami can therefore turn a clean, non-resident LLC structure into a worldwide tax-reporting nightmare.

A Simple Workflow to Stay Safe

Keep a private spreadsheet of every US entry and exit date — passport stamps and airline records are your audit trail.

Run the weighted formula each December: current year + 1/3 prior + 1/6 two-prior. If the total is anywhere near 183, talk to a US international tax adviser before year-end.

If you trip the test but have a real life and a tax home abroad, file Form 8840 with your 1040-NR by the deadline.

Never assume your visa type protects you. The substantial presence test is independent of immigration status; it counts physical presence, full stop.

Have Questions About Your Own Situation?

Day-counting rules are simple in theory and easy to get wrong in real life — especially when you are running an Amazon, Shopify or services business from outside the US and travelling in regularly. Our team can walk through your specific travel pattern, your LLC structure, and whether Form 8840 should be part of your annual filings — no pressure, no hard sell, just clear answers.

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