Day-Count Test

States, countries, and international treaty frameworks each define "day" differently — some count any part of a day as a full day, others exclude travel days, and others have safe-harbor rules for in-transit stops. Because the specific thresholds and counting methods change by jurisdiction and over time, families should verify current rules with qualified professionals rather than relying on general rules of thumb.

For high-net-worth families who travel extensively or maintain homes in multiple locations, meticulous day-counting is not optional — it is a core administrative discipline. A hypothetical example: a founder who sold her logistics company and now splits time among a Florida home, a Colorado ski property, and a New York City apartment could inadvertently cross a statutory-residency threshold in New York if business meetings keep her in the city longer than planned in a given year.

Technology tools such as calendar applications and phone location logs are sometimes used to reconstruct travel records, but contemporaneous documentation is generally considered far more reliable in an audit. Families managing complexity across multiple residences may find complexity, not net worth a useful framing for understanding why administrative rigor matters. A qualified tax attorney or CPA should review any family's travel pattern against current jurisdictional rules.