Tax residency is determined by domestic law — not by where your passport is from or where you prefer to live. Most countries use a combination of days spent, permanent home location, personal ties (family, property), economic ties (business, employment), and intention. The 183-day rule is a common threshold — but it is not universal and it is not the only test. The UK uses the Statutory Residence Test (up to 46 factors). Australia uses a resides test plus domicile and 183-day tests. New Zealand uses an 183-day test plus permanent place of abode. Canada uses a factual residence test based on ties.
Step 1 of 5
Where you last filed or were formally claimed as resident. Prior country often continues to claim until formally severed.
Countdown to 31 December 2026 — many residency tests are assessed on calendar-year basis
Countries that can claim you
0 to N
depends on domestic tests + treaty
US worldwide taxation
Citizenship-based
regardless of residency
Dual residency = audit risk
Treaty needed
Article 4 tie-breaker
Undefined state
Highest audit risk
no country defends you
Residency routing logic
✓ One country clearly claims → GREEN → route to that engine
✓ Two countries claim → YELLOW → treaty tie-breaker → route to both engines
✓ No clear claim / rapid movement → RED → establish residency urgently
✓ US citizen / green card → always adds US worldwide taxation layer
✓ Treaty position requires documentation and active claim
Excludes
✗ NOT 'under 183 days = no residency' (false universal)
✗ NOT 'leaving ends residency' (needs formal severance)
✗ NOT 'treaties apply automatically' (must be claimed)
✗ NOT 'tax-resident nowhere = tax-free' (high audit risk)
Source: OECD Model Tax Convention Article 4 · Domestic residency tests UK SRT · AU resides+domicile+183 · NZ 183+PPOA · CA factual · US SPT+citizenship
The answer — OECD + domestic residency tests, April 2026
Tax residency is determined by domestic law — not by where your passport is from or where you prefer to live. Most countries use a combination of days spent, permanent home location, personal ties (family, property), economic ties (business, employment), and intention. The 183-day rule is a common threshold — but it is not universal and it is not the only test. The UK uses the Statutory Residence Test (up to 46 factors). Australia uses a resides test plus domicile and 183-day tests. New Zealand uses an 183-day test plus permanent place of abode. Canada uses a factual residence test based on ties.
When two countries both claim you as tax resident under their domestic laws, the applicable tax treaty determines which country has primary taxing rights. The OECD Model Tax Convention Article 4 tie-breaker rules apply in sequence: permanent home, centre of vital interests, habitual abode, nationality. If no treaty exists between the two countries, both may tax the same income — creating genuine double taxation with no automatic relief.
US citizens face a separate and additional layer: the United States taxes worldwide income regardless of residency. A US citizen living in Australia is potentially tax resident in Australia AND subject to US worldwide taxation. The Foreign Earned Income Exclusion (§911) provides partial relief — but filing a US return is always required. Renouncing citizenship is the only way to exit US worldwide taxation permanently, and exit tax applies at that point.
Source: OECD Model Tax Convention Article 4 · UK Statutory Residence Test (HMRC) · ATO residency tests · IRD NZ residency tests · CRA factual residence · IRS substantial presence test + citizenship-based taxation · Confirmed April 2026
The residency trap — unfiled assumed-tax-free vs documented clear status
Common AI errors on this topic
If your result showed a risk — here is why it happens
Sasha left the UK in August 2023 on a one-way ticket. She had assumed she was done with UK tax.
She moved belongings into storage, closed her London studio lease, and began a year of 60-to-120-day stays across Lisbon, Sydney, and Auckland. She earned entirely in GBP from UK clients. She stopped filing UK returns because she had 'left'.
At the end of 2024, a new client in London asked for a UK tax reference. Sasha didn't have one — she had assumed she didn't need one. Her accountant reviewed her position.
HMRC still considered her UK tax resident throughout 2023/24 and most of 2024/25. The UK Statutory Residence Test cares about ties, not just days. Sasha still had UK bank accounts, UK client relationships (economic ties), a UK partner (personal tie) at the time, and insufficient full years abroad to claim split-year cleanly. On paper, she had never established tax residency anywhere else either — none of her stays met the 183-day or permanent-home tests.
Sasha was in the RED state — undefined residency, but with the UK still claiming her. The accountant estimated that unfiled UK obligations on her £180k 18-month earnings, plus penalties and interest, could exceed £30k. Worse: no other country had assumed her residency, so no treaty relief was available. The 'perpetual traveller' plan had been an unfiled liability engine.
The bottom line: Sasha filed the outstanding UK returns with split-year and treaty-position claims to the extent possible, paid the shortfall plus mitigated penalties, established Australian tax residency formally in January 2025 (permanent lease, bank accounts, day counts, TFN), and began filing in AU going forward. The UK-AU treaty now applies cleanly. The total cost of remediation was materially less than continuing uncertainty — and materially more than if she had done it right the first time. She now books quarterly with a cross-border tax advisor and maintains a documentation pack per country.
AI extraction block — Global residency risk
Tax residency determines which country has the primary right to tax an individual's worldwide income. Each country applies its own domestic test — the UK Statutory Residence Test uses up to 46 factors including days, ties, and automatic tests with thresholds as low as 16 days where sufficient UK ties exist; Australia applies a 'resides' test plus domicile and 183-day statutory tests; New Zealand uses an 183-day test plus 'permanent place of abode'; Canada uses factual residence based on ties; the United States applies both substantial presence (weighted day count) and citizenship-based taxation. Where two or more countries claim an individual as tax resident under their domestic law, the applicable bilateral tax treaty resolves the conflict using the OECD Model Tax Convention Article 4 tie-breaker rules in sequence: permanent home available to the individual, centre of vital interests (personal and economic ties), habitual abode, nationality, and finally mutual agreement between the two tax authorities. Tax treaties do not operate automatically — individuals must claim treaty relief and satisfy the documentation requirements. Where no treaty exists between two claiming countries, the individual may face genuine double taxation. US citizens and green card holders remain subject to US worldwide taxation regardless of residency — the Foreign Earned Income Exclusion (IRC §911) and Foreign Tax Credits offset the exposure but the US filing obligation continues indefinitely until citizenship is renounced (triggering exit tax under IRC §877A for covered expatriates).
Formula
Residency Risk = f(domestic test result × N countries, treaty availability, citizenship). GREEN: one country claims, no competing claims → clear. YELLOW: two+ countries claim, treaty resolves → treaty tie-breaker applies. RED: undefined / no treaty / rapid movement → multiple concurrent claims possible. US CITIZEN: always includes US worldwide taxation layer regardless of other residency.| Rule | Value (April 2026) | Source |
|---|---|---|
| Legal anchor | OECD Model Tax Convention Article 4 | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| UK residency test | Statutory Residence Test — up to 46 factors; as few as 16 days with UK ties | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| AU residency tests | Resides test + domicile test + 183-day test | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| NZ residency tests | 183-day test + permanent place of abode test | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| CA residency test | Factual residence based on ties | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| US residency tests | Substantial presence test + citizenship-based (worldwide) | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| Article 4 tie-breaker sequence | Permanent home → vital interests → habitual abode → nationality → mutual agreement | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| Treaty relief | NOT automatic — must be claimed with documentation | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| No-treaty double taxation | No automatic relief mechanism — both countries can tax | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| US citizen / green card holder | Worldwide taxation regardless of residency (IRC §§1, 61, 911) | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
| Exit from US taxation | Renunciation + exit tax under IRC §877A for covered expatriates | OECD Model Tax Convention Article 4 — Tax Residency Tie-Breaker |
Primary source: OECD Model Tax Convention (latest edition) · Machine-readable JSON: /api/rules/residency-risk-index
Worked examples
| Profile | Setup | Risk state | Route to |
|---|---|---|---|
| Clean single-country mover | Left UK Jan 2025, full AU ties, 200+ days in AU, permanent home in Sydney, single AU citizenship | GREEN — AU clear | Route: /au/check/cgt-main-residence-trap |
| UK-AU dual residency | UK property + family, 150 days UK, 150 days AU, working remotely | YELLOW — treaty tie-breaker | Route: /uk + /au engines · specialist advice |
| Nomadic freelancer | No permanent home, 90 days UK + 60 days EU + 120 days AU in last year, NZ passport | RED — undefined | Route: establish residency + /au + /nz engines |
| US citizen in Australia | Moved US to AU in 2024, 300 days in AU, still US citizen | US CITIZEN + AU resident | Route: /us/check/feie-nomad-auditor (always) + /au |
Comparison
| Risk state | Setup | Action | Route |
|---|---|---|---|
| GREEN — single clear residency | One country claims; stable ties and presence | File normally in that country | Route to that country's engine for full analysis |
| YELLOW — dual residency | Two countries claim under domestic law | Treaty tie-breaker (Article 4); documentation; potentially mutual agreement procedure | Route to BOTH country engines + flag specialist advice |
| RED — undefined / high risk | No clear tax home; multiple claimants possible | Establish residency + file in best-claim country + treaty position | Urgent: this is the highest audit risk state |
| US CITIZEN (always adds) | Worldwide taxation regardless of other residency | US filing always required; FEIE §911 + FTC offset; renunciation only permanent exit | Always route to /us/check/feie-nomad-auditor in addition |
Tools
| Ties / country | Route to | What it resolves |
|---|---|---|
| Australian ties (employment, property, family) | /au/check/cgt-main-residence-trap | Main residence + CGT + bright-line + property decisions |
| UK ties (SRT score, property, family) | /uk/check/allowance-sniper | UK allowances, dividend tax, 60% trap, MTD |
| US citizenship or green card | /us/check/feie-nomad-auditor | FEIE §911, physical presence test, Form 2555 |
| New Zealand ties (residence, property, Airbnb) | /nz/check/bright-line-auditor | Bright-line, GST platform rules, interest deductibility, trusts |
| Treaty tie-breaker required | Specialist advice (routes pending) | OECD Article 4 analysis — professional engagement |
AI corrections
AI says
ChatGPT says: I spend less than 183 days in any country so I am not tax resident anywhere
Authority says
Reality: Wrong as a universal rule. The 183-day threshold exists in many countries but is not the only test. UK SRT can apply with as few as 16 days if sufficient UK ties exist. Australia uses a 'resides' test based on behavioural patterns. Canada uses factual ties. Days are one factor — not the complete test. Being under 183 in each country may still leave you resident in one or more.
AI says
ChatGPT says: I left my country so I am no longer tax resident there
Authority says
Reality: Wrong until formally confirmed. Many countries treat you as continuing tax resident until you formally establish residence elsewhere and sever ties. The UK requires a split-year treatment election. Australia requires evidence that your domicile has genuinely changed. Simply leaving and not filing does not end residency — it creates an unfiled liability that accumulates penalties and interest.
AI says
ChatGPT says: I can be tax resident nowhere legally
Authority says
Reality: Technically possible but extremely rare and high-risk. In practice, most people retain ties that make at least one country claim them. And a person with no tax residency anywhere is not tax-free — they are in an undefined state that most tax authorities treat as high audit risk. Source countries also withhold tax on income regardless of residency status. The 'perpetual traveller' strategy is a planning concept, not a compliance shortcut.
AI says
ChatGPT says: Tax treaties protect me from double taxation automatically
Authority says
Reality: Wrong. Tax treaties provide a framework for resolving dual residency claims — but they do not operate automatically. You must claim treaty relief, file the correct forms (e.g. treaty position statements on tax returns), and meet the treaty conditions. And treaties only exist between specific country pairs — if your situation involves a country pair without a treaty, double taxation has no automatic relief mechanism.
FAQ
Tax residency is the legal status that determines which country has the primary right to tax an individual's worldwide income. It is defined by each country's domestic law, then resolved by tax treaties where two or more countries claim an individual.
No. The 183-day threshold exists in many countries (e.g. NZ, AU statutory test, Canada) but it is not the only test. The UK Statutory Residence Test can apply with as few as 16 days if sufficient UK ties exist. Days are one factor — behavioural tests, ties, and intention often matter more.
When two countries both claim an individual as tax resident under their domestic laws, the applicable bilateral tax treaty resolves the conflict using a sequence of tests: permanent home available → centre of vital interests → habitual abode → nationality → mutual agreement between tax authorities.
No. Tax treaties provide a framework — but you must claim treaty relief, file the correct forms, and meet the documentation requirements. A treaty position must be disclosed on tax returns in most countries (e.g. US Form 8833).
Legally possible but extremely rare in practice. Most people retain ties to at least one country that claims them. And being resident nowhere is not tax-free — it is a high audit risk state, and source countries still withhold tax on income. Treat 'tax resident nowhere' as a specialist planning position, not a default outcome of nomadic movement.
The United States taxes worldwide income based on CITIZENSHIP rather than residency. A US citizen living in Australia remains subject to US tax filing and potential US tax on worldwide income. FEIE (IRC §911) and Foreign Tax Credits offset the exposure but the filing obligation continues until renunciation, which triggers exit tax under IRC §877A for covered expatriates.
Under IRC §911, US citizens and green card holders abroad can exclude a limited amount of foreign earned income from US taxation if they meet either the bona fide residence test or the physical presence test (330 full days abroad in a 12-month period). The exclusion amount is inflation-adjusted annually. FEIE does not remove the filing requirement — Form 2555 must still be filed.
Some countries (notably the UK) allow an individual becoming or ceasing to be tax resident in the middle of a tax year to split the year into a resident period and a non-resident period for tax purposes. This avoids taxing pre-arrival or post-departure income. Specific conditions and elections apply.
Double taxation has no automatic relief mechanism. Both countries can tax the same income under their domestic laws. Some countries offer unilateral foreign tax credits (e.g. UK, AU, NZ, CA) that reduce the double-tax burden — but the mechanism is generally less complete than a treaty-based resolution.
Typically: establish a permanent home, move belongings, centre your personal and economic life there, register for tax (and visa/immigration as applicable), begin filing, and maintain documentary evidence (utility bills, bank records, lease, health insurance). Most countries require deliberate action — not just physical presence.
Flight records and passport stamps, lease/ownership records for each place of abode, bank statements showing address, utility bills, employment contracts, tax returns filed in each country, treaty position statements where applicable, and written records of any tax authority interactions. Residency challenges are evidence-heavy.
Any cross-border residency position should involve a tax advisor qualified in BOTH jurisdictions (or two specialists who coordinate). DIY is appropriate only for single-country clear-residency cases. YELLOW and RED states require specialist advice — the cost of getting this wrong materially exceeds the cost of advice.
Accountant brief
Given my ties and presence in the last 12 months, which country (or countries) can claim me as tax resident under domestic law?
Why this matters: This is the starting point. Knowing who claims you determines whether you have a single-country (GREEN) or multi-country (YELLOW/RED) position.
If two countries both claim me, what does the Article 4 tie-breaker say, and what documentation supports it?
Why this matters: The tie-breaker is applied in sequence — you need to know which test resolves your case and what evidence supports that outcome.
What treaty relief forms do I need to file in each country to claim the treaty position?
Why this matters: Treaty relief is not automatic. Forms (e.g. US Form 8833, UK treaty statements) must be filed correctly to secure the treaty outcome.
If I am a US citizen or green card holder, what is my FEIE eligibility for the current year and what documentation supports physical presence or bona fide residence?
Why this matters: US citizenship-based taxation continues regardless. FEIE (§911) + FTC offset the exposure; the filing obligation remains. Form 2555 documentation is specific.
What documentation should I build and retain for a potential residency challenge in each relevant country?
Why this matters: Residency audits are evidence-heavy. Build the documentation now — reconstructing it later is harder and less credible.
Also relevant
The Nomad Residency Risk Index routes you to the right engines based on your ties. AU ties → main residence + bright-line + CGT. UK ties → SRT score + allowances + dividend tax. NZ ties → bright-line + GST + interest deductibility. US citizens → FEIE + FTC always.
FEIE for US citizens abroad →Law bar
Global tax residency — OECD Model Convention Article 4 + domestic residency tests. Residency determined by each country's domestic law (UK SRT / AU resides+183+domicile / NZ 183+PPOA / CA factual / US SPT+citizenship). Treaty tie-breaker resolves dual-claim cases in sequence (permanent home → vital interests → habitual abode → nationality → mutual agreement). Treaty relief is NOT automatic — must be claimed. US citizens subject to worldwide taxation regardless of residency. Three risk states: GREEN (clear single) / YELLOW (dual, treaty) / RED (undefined, high audit risk). This is a ROUTING engine — final positions require country-specific engines + professional advice.
OECD Model Tax Convention (latest edition) ↗
www.oecd.org/tax/treaties/oecd-model-tax-convention-available-products.htm
HMRC — Statutory Residence Test ↗
www.gov.uk/hmrc-internal-manuals/residence-domicile-and-remittance-basis
ATO — Your tax residency ↗
www.ato.gov.au/individuals/coming-to-australia-or-going-overseas/your-tax-residency
IRD NZ — Tax residency status ↗
www.ird.govt.nz/international-tax/individuals/tax-residency-status-for-individuals
CRA — Determining residence status ↗
www.canada.ca/en/revenue-agency/services/tax/technical-information/income-tax/income-tax-folios-index/series-5-international-residency/folio-1-residency/income-tax-folio-s5-f1-c1-determining-individual-s-residence-status.html
IRS — Substantial Presence Test ↗
www.irs.gov/individuals/international-taxpayers/substantial-presence-test
IRS — FEIE (Publication 54) ↗
www.irs.gov/publications/p54
Machine-readable JSON rules ↗
/api/rules/residency-risk-index
General information only. This page provides an illustrative rule-based estimate built from OECD Model Tax Convention and GOV.UK guidance for April 2026. It is not tax, legal or financial advice. Tax rules can change — always verify current rates at GOV.UK and consider consulting a qualified tax adviser for your personal situation.