Three concepts are often confused into one, and the confusion has real financial consequences:
Citizenship — which passport you hold.
Legal residency — which country you are permitted to live in.
Tax residency — which country you must file and pay taxes to.
These three do not necessarily overlap. A person can hold a Grenadian passport, have a Portuguese residence permit, and still be a tax resident of Vietnam. Or the reverse.
How Tax Residency Is Determined
Each country has its own criteria, but most use one or more of these four categories:
Days present. The common threshold is 183 days in one year, but not all countries use this number, and the counting methods differ—some count calendar years, others count 12 consecutive months.
Primary residence. You own or rent a place to live and have it available for use.
Center of vital interests. Where your family lives, where your children attend school, where your main assets are, where your business operates.
Citizenship. Very few countries use this alone, but the United States is a major exception: U.S. citizens and green card holders must file global income taxes regardless of where they live. This is something many people planning to move to the U.S. do not anticipate.
Real Consequence: You Can Be a Tax Resident of Two Countries Simultaneously
This is not a rare situation. It happens when you spend enough days in a new country to qualify as a tax resident there while still maintaining a home, family, and business in your country of origin.
In this case, the same income can be subject to tax claims from both countries.
Tax Treaties Can Help, But They Don't Apply Automatically
Vietnam has tax treaties with many countries designed to prevent double taxation. These treaties contain rules to determine which country you are a tax resident of when both claim the right to tax.
Two important points:
Not every country has a treaty with every other country. Many Caribbean nations and some territories do not. Without a treaty, there is no mechanism to resolve conflicting claims, and the risk of double taxation is real.
Treaties don't apply automatically. You must file, provide evidence, and request a tax residency certificate from the tax authority. Without doing this paperwork, the treaty won't help.
Four Common Situations
You have a Caribbean passport but still live in your country of origin. This typically doesn't change your tax status—you remain a tax resident of your original country. A second passport is for travel; it doesn't automatically create new tax obligations.
You have a European residence permit but spend only seven days per year there. This is the model of Portugal's golden visa. You usually won't become a tax resident there, but you must verify the specific rules—some countries have lower thresholds than expected.
You move your entire family abroad. This is when your tax status actually changes. Plan this before you move, not after.
You get a U.S. green card. Your obligation to file global income taxes with the U.S. begins immediately, even if you haven't yet moved there. This is something to discuss with a tax professional before you submit your application, not after you get the card.
Recurring Costs Nobody Mentions Upfront
Annual accounting and tax consulting in your new country. For someone with income from multiple countries, this is a significant recurring expense, not a one-time cost.
Foreign asset reporting requirements. Many countries require tax residents to disclose foreign accounts and assets, with steep penalties for non-disclosure.
Compliance costs from multiple statuses. The more statuses you hold, the more reporting obligations you incur, even if you owe zero taxes.
What We Don't Do
We do not provide tax advice, and we shouldn't. This field requires professionals with specialized expertise and professional liability for their opinions.
We also don't support structures designed to hide income or assets. Beyond the ethics of it, automatic information exchange mechanisms between countries have been in place for years, so these kinds of structures are increasingly easy to detect.
Three Questions to Ask Before Signing Anything
Will this program make me a tax resident of that country, and to what extent?
Does my country of origin have a tax treaty with this country to prevent double taxation?
After I obtain the documents, what filing obligations do I face each year, and what is the approximate annual cost of compliance?
An immigration consultant can answer the first two questions. For the third, consult a tax professional—and do so before you commit funds.
If a provider says "that won't affect you" without asking detailed questions about your income structure and assets, they've never dealt with the consequences of not addressing this upfront.