Residance: Track Tax Residency

If you're managing tax residency across multiple states or countries, there's one deceptively simple question that matters more than almost anything else:

What actually counts as a day?

Most people assume the answer is obvious.

You were there, so it counts.

You weren't there, so it doesn't.

In practice, residency rules can be considerably more precise than that.

Different jurisdictions use different definitions. Some count any part of a day. Some use specific exceptions. Others apply rolling calculations or additional tests that make the calendar year only part of the equation.

If your planning depends on staying below a threshold, understanding how your days are actually counted is essential.

A Day Doesn't Always Mean 24 Hours

This is the first misconception to eliminate.

Many residency tests do not require you to spend a full 24 hours in a jurisdiction for the day to count.

For example, New York generally treats any part of a day spent in the state as a day of presence for its statutory residency test. Its guidance specifically notes that someone can be physically present in New York for part of a day and have that day count toward the 184-day threshold.

That has obvious implications for highly mobile individuals.

A morning meeting in New York followed by an evening flight to Florida may still be a New York day.

The question isn't how long you stayed.

It's how that jurisdiction defines presence.

The 183-Day Rule Isn't Actually One Rule

This is another reason residency planning gets complicated.

The phrase "183-day rule" is often used as shorthand for residency thresholds, but different jurisdictions calculate presence differently.

The IRS's federal substantial presence test, for example, uses a three-year weighted formula for certain non-U.S. citizens: all current-year days, one-third of the prior year's days, and one-sixth of the second prior year's days. It also requires at least 31 days of presence in the current year.

That's very different from simply counting 183 days in a single calendar year.

And state rules can be different again.

The takeaway:

Never assume that "183 days" means the same thing everywhere.

Arrival and Departure Days Can Matter

For some tests, entering a jurisdiction in the morning and leaving that evening can still produce a full day of presence.

New York is a clear example.

For the statutory residency test, any part of a day is generally counted as a day in New York.

That makes travel days particularly important for people who regularly move between multiple residences.

A schedule that looks like:

Florida → New York → London

might create different day counts in different jurisdictions depending on exactly when and how the travel occurred.

The details matter.

But Some Jurisdictions Recognize Specific Exceptions

There are situations where physical presence doesn't count — or may be treated differently.

The IRS, for example, provides specific exceptions under the federal substantial presence test for certain days, including qualifying transit through the U.S. of less than 24 hours between foreign destinations and certain medical circumstances that prevent a person from leaving as intended. There are also specialized rules for certain visa holders and commuters.

These exceptions are narrowly defined.

They shouldn't be treated as a general rule that "travel days don't count" or that an unexpected circumstance automatically removes a day.

The exact test and documentation requirements matter.

A Day Can Matter Even When Residency Isn't Determined by Days Alone

This is where the conversation gets more interesting.

Physical presence is often one component of a residency analysis — not necessarily the entire test.

California, for example, determines residency based in part on whether someone is present in California for a purpose other than a temporary or transitory one, or is domiciled there but outside the state for a temporary or transitory purpose. California's guidance emphasizes that additional factors are considered.

So even perfect day counting doesn't necessarily answer the broader question:

Are you a resident?

It answers a narrower — but extremely important — question:

Where were you physically present, and for how long?

The Problem Gets Harder with Multiple Jurisdictions

Imagine someone who spends the year moving between:

Florida
New York
California
London
Dubai

Now consider a typical month.

A business trip might involve three states and two countries in five days.

A weekend could begin in Florida, include a dinner in New York, and end overseas.

At that level of mobility, manually reconstructing the year becomes surprisingly difficult.

And the consequences of getting it wrong aren't necessarily symmetrical.

One missed day may be irrelevant in one jurisdiction and materially important in another.

Your Travel Records Become Evidence

This is why contemporaneous records matter.

When residency is questioned, authorities may ask you to substantiate where you were.

Your records might include:

Flight itineraries
Passport records
Hotel stays
Credit card transactions
Toll records
Vehicle records
Calendar entries
Location records

The more jurisdictions you're managing, the more important it becomes to maintain a reliable primary record of your physical presence.

You don't want to reconstruct the year from memory after the fact.

Don't Confuse Tracking with Legal Determination

There's an important distinction between tracking days and determining residency.

A tracking system can tell you where you were.

It cannot, by itself, determine whether a particular jurisdiction considers that presence sufficient to establish residency.

That's a legal and tax question.

The same physical presence can have different consequences depending on the jurisdiction, your domicile, the property you maintain, your purpose for being there, and other facts.

That is why day tracking should support — not replace — professional tax and legal advice.

Margin Matters Even More When the Rules Are Complicated

If you believe you have exactly one day of margin, you don't really have much margin.

A travel delay can change your schedule.

An unexpected meeting can add a day.

A change in plans can create another overnight stay.

And a jurisdiction's definition of presence may not match the way you intuitively think about your travel.

The closer you operate to a threshold, the more important precise tracking becomes.

And the more valuable a reasonable buffer can be.

Where Residance Fits

This is exactly the problem Residance is designed to solve.

Residance continuously tracks where your time is being spent and organizes that information across states and countries.

You can see:

Where you've been
How many days you've accumulated
How close you are to configured thresholds
Where you have planned future stays
How your travel is affecting your overall residency picture

The goal isn't to tell you whether you're legally a resident.

It's to make sure you never have to wonder where your days went.

Final Thought

A "day" isn't always as simple as midnight to midnight.

Different jurisdictions count presence differently. Some count partial days. Some use weighted formulas. Some provide narrowly defined exceptions. And many residency systems consider factors beyond physical presence altogether.

That's why sophisticated residency planning starts with a simple discipline:

Know exactly where you were.

Then understand how each jurisdiction treats those days.

Because before you can manage your residency exposure, you need to get the underlying facts right.