The types of tax-residency rules, explained
There are really only a few shapes of residency rule in the world, and once you recognize the shape you understand the test. A simple day count triggers at a fixed threshold in a fixed period. A weighted formula, like the US Substantial Presence Test, blends several years. A rolling window, like Schengen's 90/180, moves forward every day. A days-plus-abode rule, used by New York and several other states, needs both presence and a home. And a facts-and-circumstances test, like California's, weighs your whole life with no clean number.
This hub breaks down each rule type, links the jurisdictions that use it, and points you to the calculator that handles it.
Rule types
- 183-day ruleThe 183-day rule is the most common tax-residency threshold worldwide. Here's the full list of countries and US states using it, with the specific threshold each applies.
- Substantial Presence TestThe Substantial Presence Test is a 3-year weighted day-count formula used by the US to determine tax residency for non-citizens. Current-year days at full weight, prior-year at 1/3, two-years-prior at 1/6.
- Rolling windowRolling-window rules count days within a moving window (e.g., 90 days in any 180-day period for Schengen). The window moves forward each day, making them harder to plan around than calendar-year rules.
- Statutory Residence Test (UK)The UK SRT is a three-stage residency test: automatic non-resident tests, automatic resident tests, then a sufficient-ties test using day count plus UK ties.
- Days + Abode (statutory residence)States like New York, New Jersey, Massachusetts, Connecticut, and Pennsylvania trigger statutory residence based on 184+ days AND maintenance of a permanent place of abode. Both conditions must be met.
- Facts and circumstancesFacts-and-circumstances residency tests examine the totality of your connections, home, family, business, ties, rather than applying a fixed day-count threshold. California is the most prominent example.
In-depth guides
- Defending a residency audit: timeline, evidence, and what auditors actually do12 min read
- Tax Days vs. Topia: a comparison for individual cross-border residents6 min read
- The remote worker's multi-state tax guide: nexus, day counts, and double tax11 min read
- Tax Days vs. Domicile365: feature, price, and privacy comparison7 min read
- Tax Days vs. iReside: which residency tracker is right for you?7 min read
- The expat day counter guide: residency, treaties, and the rules you'll actually face12 min read
- Tax Days vs. TaxBird: which residency tracker is right for you?7 min read
- Tax Days vs. Monaeo: an honest comparison8 min read
- How Snowbirds Should Track Tax Days: US States and the US-Canada Border12 min read
- Year-End Residency Review: A December Audit-Prep Checklist10 min read
- Tax Residency for Yacht Crew & Pilots: Seafarers' Earnings & Day Counting11 min read
- Which Tax Residency Rules Apply to You? State + Visa + Test Matrix10 min read
- Schengen Overstay Penalties & Tax Implications9 min read
- Perpetual Traveler Tax Status: Myth vs Reality10 min read
- Medical, Exempt & Military Days: Official Rules by Jurisdiction10 min read
- April Tax Deadline & Residency Audit Season: A Planning Guide10 min read
- Schengen 90/180 with Multiple Passports: Can You Reset Your Count?9 min read
- Tax Residency for Retirees: Social Security, Medicare IRMAA & Domicile10 min read
- Tax residency audit defense: the evidence hierarchy and what precedent rewards11 min read
- New Year Tax Residency Planning: The 2026 Checklist for Snowbirds & Expats10 min read
- Dual Citizens & Treaty Tie-Breakers: When the US Saving Clause Overrides11 min read
- Tax Residency for Crypto Traders: Capital Gains by Jurisdiction & the 30% Trap11 min read
- Tax Residency Spreadsheet vs App: Why Google Sheets Won't Survive an Audit9 min read
- Tax Residency Edge Cases: Do Layovers, Partial Days & the Midnight Rule Count?10 min read
- How Many Days Can I Spend in a Country Before Becoming a Tax Resident?10 min read
- Best Tax Residency Tracker Apps 2026: Complete Comparison10 min read
- The digital nomad tax guide: residency, Schengen, and the rules that catch you12 min read
- How the 183-day rule decides your tax residency9 min read
Frequently asked questions
What is the most common type of tax-residency rule?
The simple day count: spend more than 183 days in a calendar year and you're a resident. Most countries and many US states use a version of it.
How is the Substantial Presence Test different from a 183-day rule?
The SPT is weighted across three years, all of this year's days, a third of last year's, and a sixth of the year before, so it catches people who cycle through the US repeatedly even if no single year exceeds 183 days.
Track all of it in one app
Tax Days runs every rule in this guide on your iPhone, a live day count across US states, federal SPT, Schengen, and 200+ countries.
