The calendar
is a tax form
Spend enough days here and two tax systems claim you — federal by the substantial presence formula, New York by its own 183-day rule. Owners near the lines need the counting discipline.
Before you read on
- General information as of August 2026. Residency determinations are facts-and-circumstances — advisers rule on real cases.
- Not tax advice.
- The two tests differ — Section 2's distinction prevents the common conflation.
Point 1The federal test: substantial presence
The formula: 183 weighted days across three years — this year's days plus one-third of last year's plus one-sixth of the year before — with 31 current-year days as the trigger threshold. Cross it and you are a US tax resident by default: worldwide income filing, FBAR and information returns, the full resident machinery — ownership of property contributing nothing, presence contributing everything.
The escape valves: the closer-connection exception (under 183 actual current-year days, a foreign tax home, and the closer-connection facts — claimed on Form 8840 annually, not automatic), treaty tie-breakers for the dual-resident (the treaties chapter's provisions deciding which country claims you), and exempt-day categories (students, diplomats, medical emergencies — narrow and documented). The rhythm many part-time owners run — roughly four months annually — sails near the formula; the counting below is their discipline.
Point 2New York's own claim
The state's separate test: statutory residency — 183-plus New York days and a permanent place of abode here — captures your worldwide income for New York tax regardless of federal status or domicile elsewhere. The apartment is the abode half automatically; the days are the controllable half, and the audit machinery around them is famously aggressive: cell records, card transactions, and building access logs subpoenaed in residency audits that treat any part of a day in the state as a New York day.
The conflation to avoid: the federal weighted formula and New York's actual-day count are different tests with different arithmetic — clearing one clears nothing about the other. The pied-à-terre owner working occasional Manhattan weeks can pass federal comfortably while stumbling into the state's count; the near-the-line owner runs both counters.
Point 3The counting discipline
The buffer philosophy: day-counting to the line invites the miscounted trip, the medical extension, the audit's aggressive constructions — the owners who plan to comfortable margins never litigate their calendars. The library's preparation ethos, applied to presence itself.
| Practice | Why |
|---|---|
| Contemporaneous day log | Audits demand proof; reconstruction fails |
| Any-part-of-day rule respected | Arrival and departure days count in NY's test |
| The evidence trail kept | Boarding passes, tolls, cards — the log's corroboration |
| The 8840 filed on time | Closer-connection claims are annual paperwork |
| Both counters run | Federal weighted; New York actual |
| The buffer maintained | Planning to 150, not 180 — margins beat precision |
Apps and calendars automate the log; the audit-grade version pairs it with the paper trail.
Point 4When residency is the plan
The other direction, deliberately: families intending US residency (the retirement chapter's relocations, the education chapters' accompanying parents) cross the lines on purpose — at which point the planning inverts to pre-arrival structuring (income timing, basis refreshes, the trust and gift moves best made before residency starts, per the structure chapters) and the state-selection question (the Florida-versus-New-York domicile arithmetic the Miami chapter frames).
The transition's craft is timing: the year residency starts, both systems' rules overlap in ways pre-arrival advice arbitrages and post-arrival regret cannot — the single most valuable conversation in the cross-border tax calendar happens the year before the move. The day counts are thresholds, not accidents; owners who treat the calendar as the tax form it is choose their side of every line.
The federal formula weights three years — 183 weighted days with a 31-day trigger; roughly 120 actual days annually sails clear indefinitely. The closer-connection exception extends room with annual filing.
Federally no — presence alone counts. For New York's statutory residency, the apartment supplies the 'permanent place of abode' half; your days supply the rest.
183-plus actual New York days plus an abode captures worldwide income for state tax — any part of a day counting, audited aggressively through cell and card records.
Contemporaneous logs corroborated by boarding passes, tolls, and transactions — reconstruction after an audit notice fails. Apps automate; paper corroborates.
The closer-connection exception's annual claim — foreign tax home and closer ties keeping you non-resident despite the formula. Unfiled, the exception is unavailable.
The pre-arrival year: income timing, basis refreshes, and structure moves priced before residency starts. The advice's value peaks twelve months before the move.
RELATED GUIDES
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Living near the lines — or planning to cross them? We will set up the counters, the buffers, and the pre-arrival conversation.
Important notice
The figures on this page are general information as of August 2026 and do not represent an offer, a quote, or a guarantee of any transaction terms. Reinvent NY does not provide legal, tax, or investment advice. Confirm anything material with an attorney and a CPA before you act on it. Nothing here is a solicitation to invest, and no return is promised. Real estate brokerage services are provided through R New York.