A passport is often seen as a form of freedom. It allows a person to move, live, work, invest or protect their family across borders.
But in private legal matters, nationality is never just a travel document. It can change the way a family’s wealth is taxed, inherited, reported and controlled.
This becomes especially relevant for people with more than one nationality. A person may be Spanish and Argentine, British and Portuguese, American and Italian, or hold citizenships acquired through origin, marriage, residence or naturalisation. What looks like flexibility can also create competing legal connections.
The problem usually appears when something changes: a relocation, a marriage, a divorce, the birth of children, the purchase of property abroad, the creation of a company, the sale of a business, incapacity or death. At that moment, advisers may discover that nationality affects more than expected.
Succession is one of the clearest examples. In Europe, nationality can be decisive because a person may be able to choose the law of their nationality to govern their succession. For someone with several nationalities, that choice can be powerful. It may affect forced heirship, the rights of a surviving spouse, the position of children from different relationships and the distribution of assets located in several countries.
But if that choice is not made correctly, the result may be very different from what the family expected. A person may believe that their estate will follow the law of one country, while another legal system considers itself relevant because of residence, nationality, asset location or family connections.
The consequences can be serious. A will may not operate as intended. Children may receive rights that were not anticipated. A surviving spouse may be better or worse protected than expected. Assets may be frozen while authorities, heirs or courts determine which law applies. A structure that looked coherent during life may become uncertain after death.
Tax is another layer. Nationality is not the same as tax residence, but it can still matter. Some countries attach tax or reporting obligations to citizenship. The United States is the clearest example: US citizens may remain subject to US tax and reporting obligations even if they live abroad. For dual nationals, this can affect investment accounts, companies, trusts, gifts, inheritances and the way assets are held.
Banks and financial institutions also care. Multiple passports may trigger additional compliance questions. A client may be asked to explain tax residence, beneficial ownership, FATCA or CRS status, source of funds, sanctions exposure or links to jurisdictions considered sensitive. A nationality that feels irrelevant personally may be highly relevant to a bank, trustee, insurer or investment platform.
Family law can also be affected. Nationality may influence matrimonial property regimes, recognition of marriage contracts, divorce consequences, parental responsibility and succession expectations. A couple with different nationalities, married in one country, living in another and owning assets in a third should not assume that each jurisdiction will read the family situation in the same way.
For children, the issue can be even more delicate. Parents may obtain additional nationalities for mobility, education or security. That may be sensible. But those same nationalities can later influence inheritance rights, tax reporting, military or civic obligations, ability to hold certain assets, or future residence options. What is obtained as protection for the next generation should be integrated into the family’s legal planning.
The real risk is not having several nationalities. The risk is treating them as administrative details.
Good planning starts by mapping the person before mapping the assets. Which nationalities exist? Where is the person actually resident? Where are the spouse and children based? Where are the assets located? Which law governs succession? Are there wills in more than one country? Are there companies, trusts, foundations, life insurance policies or joint accounts? Do any citizenships create tax or reporting obligations?
Multiple nationalities can be extremely useful. They can protect mobility, preserve family links and create strategic options. But they can also introduce uncertainty if they are not coordinated with residence, tax, succession and asset ownership.
A passport can open doors.
It can also change the legal consequences of everything behind them.