Expat Tax Guide 2025
How to Pay Taxes as a Remote Worker Abroad

Taxes are the part of expat life that most people either over-worry about or completely ignore — and both approaches cause problems. The reality is that international taxation follows clear rules. Understanding those rules before you move is the difference between a clean situation and years of liability in two countries simultaneously.

This guide covers the full framework: where tax liability comes from, how to manage it, country-specific systems, and the specific situations where you need professional help.

🌐 The core concept: residency vs source

Every country taxes income using one or both of two principles:

• Residency-based taxation: You owe tax to the country where you live, on all income earned anywhere in the world. This is the most common system — used by most of Europe, Australia, Canada, and many others.
• Source-based (territorial) taxation: You only owe tax to the country where income is earned. If you live in a territorial tax country and your employer is abroad, you owe nothing locally on that income. Georgia, Panama, Paraguay, Costa Rica, and Malaysia (partially) use this system.
• Citizenship-based taxation: You owe tax to your passport country regardless of where you live or where income is earned. Only two countries in the world do this: the United States and Eritrea.

📅 The 183-day rule — and its gotchas

The 183-day rule is the most cited rule in expat taxation — and the most misunderstood. Here's what it actually means and where it gets complicated.

The basic rule: In most countries, spending 183 or more days in a tax year makes you a tax resident of that country — subject to its income tax on worldwide earnings.

The gotchas:

• Not all countries use 183 days. Some have shorter thresholds: the UK uses a complex "Statutory Residence Test" that can trigger residency with as few as 16 days if you have ties there. France can trigger at 183 days or if France is your "centre of economic interests."
• Days are counted differently. Most countries count any partial day in-country as a full day. A two-hour layover doesn't usually count, but an overnight always does.
• Calendar year vs tax year. Most countries use the calendar year (Jan–Dec), but the UK uses April 6 to April 5. Spain and Germany use calendar years. This matters when your move straddles year-end.
• You can trigger residency in two countries simultaneously. If you spend 200 days in Portugal and 100 days in Germany in one year, both countries may claim you as a tax resident. This is exactly the situation DTAs are designed to resolve — but you need to know they apply.
• Some countries count days based on intent, not just presence. If you sign a 12-month lease in Germany on day 1, German tax law may treat you as resident from day 1 — even if you leave after 4 months.

🏛️ Establishing and exiting tax residency

Establishing tax residency in a new country typically requires:

• Registering your address with local authorities (Anmeldung in Germany, Anmeldelse in Denmark, etc.)
• Obtaining a local tax identification number
• In some countries, filing a declaration of tax residency or completing an initial tax return
• Meeting the days-presence threshold for the relevant tax year

Exiting tax residency in your home country typically requires:

• UK: Passing the Statutory Residence Test as non-resident — requires not meeting any of the "automatic UK resident" tests and meeting a "sufficient ties" test based on how many UK connections you retain
• Australia: Establishing a permanent home abroad, severing your Australian domicile, and ceasing to have an "Australian abode"
• Canada: Cutting residential ties — closing bank accounts, cancelling health coverage, surrendering driving licence, removing family members
• Germany: Deregistering your address (Abmeldung) and having no permanent dwelling available in Germany
• US: You cannot exit US tax liability by changing residency. You must renounce citizenship — a serious, irreversible process with exit tax implications.

📑 Double Taxation Agreements — what they actually do

A Double Taxation Agreement (DTA), also called a tax treaty, is a bilateral agreement between two countries that determines which country has the right to tax which types of income when you have connections to both.

What a DTA does:

• Establishes "tie-breaker" rules when both countries claim you as a tax resident
• Allocates taxing rights over specific income types (employment income, dividends, rental income, pensions, capital gains)
• Provides a mechanism to claim credit for taxes already paid in one country against liability in the other
• Reduces or eliminates withholding tax on cross-border dividends and interest payments

What a DTA doesn't do:

• It doesn't eliminate your obligation to file a tax return in either country
• It doesn't automatically apply — you usually need to actively claim DTA protection
• It doesn't override domestic anti-avoidance legislation
• It doesn't help if you're a US citizen — the US taxes worldwide income regardless of DTAs (though DTAs may reduce the rate on specific income types)

🏝️ Territorial tax countries — the fine print

Territorial (source-based) taxation is the holy grail for many remote workers — you live in the country, spend money locally, but owe no local income tax on your foreign-sourced income. Several countries genuinely offer this. But each has conditions that matter.

🇺🇸 US citizens abroad — the special case

The United States is one of only two countries in the world that taxes its citizens on worldwide income regardless of where they live. If you hold a US passport, you owe the IRS a filing every year for life — no exceptions, no way around it short of renouncing citizenship.

The two main tools for reducing US tax liability abroad:

The Physical Presence Test: To qualify for the FEIE, you must spend at least 330 full days outside the US in any consecutive 12-month period. Days in transit don't count. Days in the US — even for a family visit — count against your 330.

👤 Self-employed vs employee — different exposure

How you're employed dramatically affects your tax situation abroad. The rules are different and the risks are different.

📈 Capital gains, dividends, and investment income

Employment income is the most straightforward part of expat taxation. Investment income is where it gets complicated — and where many expats get caught out.

• Capital gains: Most countries tax capital gains differently from income — often at a flat rate (28% in Portugal, 19% in Spain, 25% in Germany). DTAs typically allocate capital gains taxation rights to the country of residency. If you sell shares or property while tax resident in a high-CGT country, that country taxes the gain — even if the asset is foreign.
• Dividends: Taxed at source (withholding tax) in the country where the company is based, and also potentially in your country of residency. DTAs often reduce the withholding rate. Portugal, for example, has a standard 28% flat rate on dividends for residents — but a DTA may reduce the source-country withholding from 30% to 15%.
• Pension income: Most DTAs allocate pension taxation to the country of residency, not the country where the pension was earned. This can be beneficial (low-tax country) or costly (high-tax country). Government pensions (military, civil service) are typically an exception — usually taxed only in the country that pays them.
• Rental income from home-country property: Almost universally taxed in the country where the property is located, regardless of where you live. You'll typically also need to declare it in your country of residency — but can usually claim credit for tax already paid.
• Cryptocurrency: Treatment varies wildly by country. Germany exempts crypto gains after 1 year of holding. Portugal taxed it at 28% from 2023 after previously exempting it. Always verify current rules in your country of residency — this is a fast-moving area.

❌ The most expensive mistakes expats make

• 💸
  Assuming leaving ends home-country tax liability. Not filing an exit return, not formally breaking residency, and then receiving a multi-year tax bill with interest and penalties is one of the most common and costly expat tax mistakes.
• 🏦
  Not filing FBAR (US citizens). Tens of thousands of US expats discover this obligation late. Catch-up filing via the IRS Streamlined Procedure is available for non-wilful non-compliance — but it requires filing 3 years of amended returns and 6 years of FBARs.
• 📅
  Triggering residency in two countries in the same year. Moving mid-year without understanding how each country counts days can leave you resident in both simultaneously. Plan your move date to minimize overlap — ideally completing 183+ days in the new country before year end, while having departed the home country early enough to satisfy its exit tests.
• 🧾
  Not declaring foreign income in the new country. Being tax resident somewhere and not filing a return declaring your worldwide income is non-compliance — even if no tax is ultimately owed (e.g. because of a DTA or FEIE). File the return.
• 🏢
  Creating a permanent establishment for your employer. Working remotely abroad without disclosing this to your employer can create unexpected corporate tax exposure for them — and when they find out, it often ends the employment arrangement.
• 📊
  Selling assets without considering CGT timing. If you're planning to sell a property, a share portfolio, or a business, the tax treatment can differ enormously depending on whether you do so before or after establishing tax residency in your new country. Getting the sequence right can save tens of thousands.

🧑‍💼 DIY vs hiring a cross-border tax specialist

You can probably DIY if:

• You have a simple salary from a single employer with no investment income
• You're moving to a territorial tax country and have formally exited your home country's tax residency
• You're a non-US citizen with a clean, single-country income situation
• Your total income is below the threshold that would make professional fees worthwhile (roughly: if your total tax is under $3,000, a $500 specialist may not be worth it)

You need a specialist if:

• You're a US citizen — full stop. The filing complexity alone makes specialist help valuable
• You have investment income, capital gains, pensions, or rental income from multiple countries
• You're moving mid-year and need to manage the split-year situation in two countries simultaneously
• You're selling a property or business within 1–2 years of your move
• You're self-employed and setting up a structure in a new country
• You've been non-compliant and want to regularise your situation

This guide is for educational purposes only and does not constitute tax or legal advice. International tax law is complex and jurisdiction-specific. Rules change frequently and your personal situation — nationality, income type, assets, and destination — determines your actual obligations. Always consult a qualified cross-border tax specialist before making decisions based on this guide. References to specific figures (FEIE limit, FBAR thresholds) are based on 2025 published guidance and may change.