The number everyone knows is 183. The question nobody asks until an auditor asks it for them is: what, exactly, is a day?
It sounds like pedantry. It is the whole game. Residency audits are not usually lost on the big blocks — the auditor and the taxpayer agree about January in Palm Beach and August at the lake. They are lost at the edges, in the twenty or thirty ambiguous days a travel-heavy year generates: the layovers, the midnight landings, the day trips, the drives through, the medical stays, the days that exist on no boarding pass. A snowbird whose self-count says 160 New York days and whose auditor-count says 187 didn’t mislay a month — they applied the wrong rules to the edges, thirty times.
This post is the day-counting law, plainly stated: the general rule, the exceptions that matter, and the edge cases that decide real cases.
The General Rule: Any Part of a Day Is a Day
Start with the rule in New York, Connecticut, and Minnesota, each of which has a statutory residency test: any part of a calendar day spent in the state counts as a full day in the state. Rules vary by state.
Not a majority of the day. Not an overnight. Any part. Under this rule:
- Land at LaGuardia at 11:48 p.m. → that calendar day is a New York day, all twelve minutes of it.
- Leave Manhattan at 6:05 a.m. → that day is a New York day too. An overnight stay therefore usually costs two counted days, not one.
- Step off the train in Stamford for a two-hour meeting → Connecticut day.
Notice the asymmetry this creates for the mover: the rule is generous to the state counting against you and stingy in your favor. There is no equivalent rule awarding you a Florida day for any twelve minutes in Florida — your Florida count is simply the days you were actually there, and on a travel day you can be “in” two states under two different counting postures at once. The conservative practice, and the one your advisor will tell you to adopt: count travel days against yourself on both boards. Treat the day you fly from Palm Beach to JFK as a New York day (it is, under the any-part rule) and don’t lean on it as a Florida day either. If your plan only works when the travel days break your way, your plan is too tight — build margin instead.
The Exceptions: Narrow, Specific, and Worth Knowing
The any-part rule has exceptions. New York’s guidelines name two: travel and medical. Both are specific and depend on the facts.
The travel exception. New York disregards presence that is solely for boarding a plane, ship, train, or bus for a destination outside the state, or for continuing travel, begun outside the state, by automobile, plane, or train to a point outside the state. A Connecticut resident who travels to JFK to board a plane to Europe does not count that day. Part F of New York’s Nonresident Audit Guidelines says meals or other purchases at a terminal, an ATM stop, or a stop for gas or a meal while driving through New York should not change a travel day. A visit with a friend during an unavoidable delay or stopover does not count either. Activity you control can change the answer: someone who arrives a day early for a cruise to attend a business meeting is present in New York that day. If you rely on this exception, keep the tickets and the timeline.
The medical exception. Days confined to a hospital or medical facility in the state for treatment are generally excluded from the statutory-residency day count. The exception covers the confinement — it does not stretch to outpatient visits, recuperating at the New York apartment after discharge, or accompanying a spouse to their appointments. Families dealing with a health crisis up north routinely assume the whole episode “doesn’t count.” Only the inpatient days do, and the documentation that proves it is the medical record itself.
Two warnings travel with every exception. First, they vary by state. Connecticut’s and Minnesota’s rules are not New York’s. Second, you need the facts to support them. An exception you can’t document is hard to claim.
The Edge Cases That Decide Real Audits
The undocumented day. The most important counting rule isn’t about presence at all. It’s about proof. In New York, a taxpayer who maintains a permanent place of abode has the burden of proving fewer than 184 days, and the evidence must be clear and convincing. Testimony, documents, or both can meet that burden. Part F also says auditors should generally accept a claim of being home on a weekend day absent contrary evidence, such as a clear pattern of regularly being in New York on weekends. A long gap with no transactions and no phone records leaves you to carry the burden without documents, and it is why auditors look at your cell records and not only your recollection.
The midnight problem. Days are calendar days, and calendar days end at midnight. The red-eye that departs at 11:55 p.m. and the one that departs at 12:10 a.m. produce different day counts. Nobody should schedule their life around this — but when you’re reconstructing a year, the timestamps matter, and when you’re planning a tight December, they’re worth a glance.
The “I wasn’t really there” day. Funerals, board meetings, closings: days that feel trivial. New York’s guidelines name only the two exceptions above, and they say brief presence would normally count as a day, though no audit is expected to rest on stepping over the state line for one second. The five “doesn’t really count” trips a year that every honest person mentally waives are, collectively, often the margin of failure.
The two-thresholds trap. Remember that your old state’s count and your Florida count are different boards with different stakes: the old-state board decides statutory residency under that state’s own test (in New York, more than 183 days there); the Florida board supports your 183-day domicile evidence. The edges land differently on each, which is why the honest accounting tracks every day’s actual location, not a single running total.
The Operating Practice
Compressed to four habits:
- Count every partial day against yourself in the old state, including both travel days of every trip.
- Claim exceptions only with documents — through-tickets for transit days, medical records for confinement days.
- Keep gaps few. Place as many days as you can with contemporaneous evidence, because you carry the burden on the count.
- Keep margin. If the count only clears with the edge cases breaking your way, change the calendar, not the counting.
The 183 everyone quotes is arithmetic. The “day” nobody defines is law. Audits are won by people who treated both seriously, in real time, all year.
Where Southbound Fits
Habit three is the one that can’t be done retroactively — and the one software does better than memory.
Southbound is an iOS app that records location checks automatically. It uses iOS’s significant-location-change system, not continuous GPS, and marks recorded days as Florida or non-Florida, building a contemporaneous record to help with the burden of proof. The Departure Budget keeps the running arithmetic visible as one number, and location evidence is available where checks were retained.
The record lives in your own iCloud account — Southbound runs no servers and never sees your location history — and exports as a day-by-day CSV the moment your accountant or an examiner wants to argue about August.
Southbound is on the App Store, with a 14-day free trial for eligible users. The counting rules are specific. A record kept at the time helps you apply them.
Sources: New York Nonresident Audit Guidelines, December 2021, Part F; Minnesota Department of Revenue, 183-day rule; Connecticut Regs. Sec. 12-701(a)(1)-1.
This post is for general informational purposes only and does not constitute tax or legal advice. Day-counting rules, exceptions, and burdens of proof vary by state and are applied to specific facts. Work with a qualified tax attorney and CPA for advice specific to your situation.
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Published Jul 13, 2026