Tax Residency vs Domicile vs Residence Permit: What’s the Difference?

Understanding these concepts is essential for expats, remote workers, founders, and international families because each one affects your taxes, immigration rights, and legal obligations differently. For example, you can hold a UK residence permit without becoming a UK tax resident. Or you may remain domiciled in the US while living abroad for years. These distinctions matter when navigating income taxes, inheritance rules, double taxation treaties, and visa planning. In this guide, we break down what tax residency, domicile, and residence permits actually mean — and how they interact in real-life scenarios across the US, UK, Portugal, and UAE.

What Is Tax Residency?

Tax residency — sometimes called fiscal residency or tax resident status — determines which country has the right to tax your worldwide income. Every country sets its own rules for deciding whether you qualify. In practice, tax residency is usually based on: The number of days you spend in a country Where your permanent home is located Your family and economic ties Where your "center of vital interests" exists Many countries apply some version of the 183-day rule, but the actual tax residency rules are often more nuanced than a simple day count.

The UK Tax Residency System

The UK uses the Statutory Residence Test (SRT) to determine tax residency. The test weighs: How many days you spend in the UK Whether you have a home there Work connections in the country Personal ties such as close family members Importantly, you can become a UK tax resident even if you spend fewer than 183 days in the country — if your connections are strong enough. The SRT is one of the more complex frameworks globally, and getting it wrong is expensive.

The US Tax Residency System

The US applies two main routes to tax residency: The Substantial Presence Test, which uses a weighted formula counting days spent in the US over a three-year period Holding a US Permanent Resident Card (green card) Unlike most countries, the US also taxes its citizens regardless of where they live. This means a US citizen living in Dubai or Lisbon may still need to file US tax returns — even after becoming a tax resident elsewhere.The same applies if you're relocating to Canada — US citizens moving to Canada face the same citizenship-based filing obligations. Provisions like the Foreign Earned Income Exclusion (FEIE) can reduce the actual tax owed, but the filing obligation remains.

What Is Tax Domicile?

Domicile — also referred to as tax domicile in some contexts — is a broader legal concept connected to your permanent home and long-term intentions. Unlike tax residency, domicile is rarely determined by counting days in a country. A person generally acquires: ◾A domicile of origin at birth
◾A domicile of choice, established by permanently settling in another country with the genuine intention to remain there indefinitely

Changing domicile requires proving both a physical relocation and a clear intention to make the new country your permanent home. This is a high legal bar that many long-term expats never actually clear.

Domicile vs Tax Residency: The Key Difference

This is where most people get confused.

You can live in another country for years, become a tax resident there, and still remain domiciled in your original country. The two statuses are legally independent.

For example: ◾ A US citizen living in the UK for ten years may still be considered US-domiciled for estate tax purposes
◾ A UK citizen working temporarily in New York may remain UK-domiciled even while paying US income tax

Domicile also connects closely to concepts such as habitual abode and the center of vital interests — terms that appear frequently in tax treaties when resolving dual residency disputes.

Why Domicile Matters

Domicile most commonly affects:

◾ Inheritance taxes and estate planning
◾ Succession law (which country's rules govern your assets)
◾ Certain wealth tax rules
◾ In the UK, access to the historical non-dom regime

The UK Non-Dom Regime (A Key Example)

Under rules that applied for many years, a person could live and work in the UK, qualify as a UK tax resident, and still remain domiciled abroad. This historically allowed certain individuals to avoid UK taxation on foreign income unless it was brought into the country — a treatment known as the remittance basis.

This is one of the clearest real-world examples showing that tax residency and domicile are entirely separate legal statuses that can coexist.

What Is a Residence Permit?

A residence permit is an immigration document that gives someone the legal right to live in a country temporarily or permanently. It is issued by immigration authorities, not tax authorities, and serves an entirely different purpose from the other two concepts.

Common examples include: ◾ UK Skilled Worker visas ◾ US Permanent Resident Card (Green Card) ◾ Portugal's D7 Passive Income Visa or Digital Nomad Visa ◾ UAE residence permits and Golden Visas ◾ Temporary and permanent residency permits across the EU, as outlined by the EU Immigration Portal

Temporary vs Permanent Residence Permits

A temporary residence permit typically has an expiration date, may depend on employment or study, and can include conditions or restrictions. A permanent residence permit allows long-term residence with greater stability and often creates a pathway toward citizenship.

Does a Residence Permit Create Tax Residency?

Not automatically — and this is one of the most common and costly misconceptions among expats.

A person can hold a residency permit but spend too little time in the country to trigger tax residency. Conversely, someone may spend enough time in a country to become a tax resident without ever holding a formal long-term permit.

Tax authorities typically evaluate time spent in the country, economic ties, and personal connections — independently of what any immigration document says.