How to avoid dual tax residence when living between two countries

Dual tax residence occurs when two jurisdictions, each applying its own domestic criteria, treat the same person as a tax resident at the same time. This does not require bad faith or an obvious mistake: it is enough for a person's actual routine — time spent, housing, economic ties — to simultaneously satisfy the residence criteria of more than one country.

The migration flow between Brazil and Portugal involves many people who maintain strong ties to both countries: property available in each, family split across both jurisdictions, remote or intermittent professional activity. Any one of these factors, on its own, may already satisfy one country's tax residence test, without necessarily displacing residence in the other.

Most tax systems use, among other criteria, time physically spent in the territory and the availability of a habitual dwelling. When a person does not formally organize their exit from one country upon settling in the other, it is common for both criteria to remain satisfied simultaneously.

Even when time spent is not decisive, the center of economic interests — where the main income, investments and professional activity are located — can lead a tax authority to claim the person's tax residence, generating conflict with the criterion applied by the other country.

When an agreement is in force between the two countries involved, it typically sets out tie-breaker rules to resolve dual-residence situations — such as permanent home, center of vital interests or nationality, applied in successive order. Correctly applying these tie-breaker rules depends on the specific case and requires technical analysis; it cannot be generalized without considering the particular facts involved.

• Failing to formalize tax exit from the country of origin upon settling abroad, leaving the previous classification in place by omission.
• Keeping housing available for personal use in both countries without assessing the impact on the habitual-dwelling criterion.
• Overlooking that remote-work income can create a relevant economic tie in more than one jurisdiction.
• Assuming that the existence of an agreement between the countries automatically resolves any conflict, without verifying its application to the specific case.
• Failing to reassess the situation when the person's time-spent routine changes from one year to the next.

Dual tax residence rarely stems from bad faith; it stems from a lack of formalization at the time of the move.

1. 01Clearly define which country will be treated as the main tax domicile from a given date onward.
2. 02Formalize the tax exit from the country of origin, when required by local procedure, on the correct date.
3. 03Reduce ties that would support a habitual-dwelling classification in the country that ceases to be the main domicile.
4. 04Verify the existence and validity of the double-taxation agreement between Brazil and Portugal applicable to the case.
5. 05Gather documentation evidencing the center of economic and vital interests in the country chosen as residence.
6. 06Reassess the situation annually, especially during years of transition between the two countries.

Avoiding dual tax residence is, to a large extent, a matter of planning and timely formalization, not luck. The country pages (/paises/brasil, /paises/portugal) offer a general overview of the applicable regimes, but analyzing the tie-breaker criteria and each person's situation requires dedicated technical follow-up.

Anyone already living — or about to live — between Brazil and Portugal can benefit from the International Legal Diagnosis, available at /diagnostico, to map the risk of dual residence before it turns into a tax liability.