Many Americans relocate to Portugal believing their estate planning is complete. They created a U.S. living trust, avoided probate in the United States, and assumed their structure would continue to work wherever they lived.

That assumption is often wrong.

When you become resident in Portugal, you step into a completely different legal system. Portugal follows civil law, not common law. That distinction has direct consequences for how your estate is treated at death.

If your planning was built entirely around U.S. legal principles, it may not function as intended under Portuguese civil law statutes.

The Core Problem: Civil Law Vs. Common Law

A U.S. revocable living trust is designed within a common law framework. It allows flexibility and control. You can decide who inherits your assets, when they inherit, and under what conditions. In many U.S. states, you can disinherit children or structure unequal distributions.

Portugal operates under a civil law system that prioritizes family protection over testamentary freedom. The Portuguese Civil Code imposes mandatory inheritance rules known as forced heirship.

These rules are not optional. They override private arrangements that conflict with them.

If you are habitually resident in Portugal at the time of death, Portuguese succession law may apply to your worldwide estate unless you have made a valid election under European succession rules.

Without proper coordination, your U.S. trust can collide directly with Portuguese law.

Forced Heirship in Portugal Explained

Under Portuguese law, a significant portion of your estate is reserved for your legitimate heirs. These typically include your spouse and your children. In the absence of children, ascendants such as parents may also have protected rights.

The reserved portion of the estate cannot be freely allocated. Only the remaining disposable portion may be distributed according to your personal wishes.

This means that if your U.S. living trust leaves everything to a second spouse and excludes children from a previous marriage, Portuguese law may entitle those children to a fixed share regardless of what your trust document says.

In practical terms, the trust does not eliminate their rights under Portuguese law.

Recognition Issues with U.S. Living Trusts

Portugal does not have an equivalent domestic structure to a revocable living trust. Although Portugal has signed international conventions relating to trusts, the day to day legal and administrative treatment of trusts remains complex within a civil law environment.

Portuguese notaries, land registries, and financial institutions operate under statutory rules that focus on legal ownership and mandatory heirship. Assets placed in a U.S. trust may still be treated as personally owned for succession purposes.

For example, if you hold Portuguese real estate through your U.S. living trust, the property registry may not treat the trust as a fully autonomous estate planning vehicle in the same way a U.S. court would. Upon death, heirs may still need to complete Portuguese inheritance procedures before the property can be transferred or sold.

As a result, the administrative simplicity you expected from your trust can disappear.

The Role of the EU Succession Regulation

Portugal applies the EU Succession Regulation, which allows individuals to elect the law of their nationality to govern their estate. For U.S. citizens living in Portugal, this can provide an important planning tool.

However, this election must be clearly stated in a valid will. It is not automatic. If no election is made, Portuguese law may apply by default if Portugal is your habitual residence at the time of death.

Even when a nationality election is properly made, coordination remains essential. The interaction between Portuguese property law, U.S. estate tax exposure, and local administrative practice must be carefully reviewed. An election alone does not solve every structural issue.

Tax Considerations Across Two Systems

Portugal does not impose a traditional inheritance tax, but it does apply stamp duty on certain gratuitous transfers. Transfers to spouses and direct descendants are generally exempt, while transfers to others may be taxed.

At the same time, U.S. citizens remain subject to U.S. federal estate tax on their worldwide assets, regardless of residence.

This means your estate may be exposed to two separate tax systems. A U.S. trust that was efficient for domestic purposes may not account for Portuguese stamp duty rules or the practical realities of estate administration in Portugal.

Cross border succession planning must consider both jurisdictions simultaneously.

Where Problems Usually Surface

The legal issues often remain hidden until death. That is when families discover that:

• Children have mandatory rights that were not anticipated.
• A surviving spouse faces unexpected claims.
• Portuguese property cannot be immediately transferred or sold.
• Banks require formal heirship procedures before releasing funds.
• Delays increase costs. Uncertainty increases conflict.

What was meant to provide clarity becomes a source of stress at the worst possible moment.

What Proper Cross Border Planning Requires

Effective cross border succession planning for U.S. citizens in Portugal typically involves coordinated documentation in both jurisdictions. This may include a Portuguese compliant will that properly elects the law of nationality, alignment between the U.S. trust and Portuguese assets, and a clear asset holding strategy that reflects local registration rules.

Tax exposure must be reviewed in both countries. Liquidity planning should ensure that estate expenses, debts, and potential taxes can be paid without forcing the sale of key assets under pressure.

The goal is not to discard a U.S. living trust. It is to integrate it into a structure that respects Portuguese civil law realities.

The Bottom Line

A U.S. living trust is not automatically invalid in Portugal. However, it is rarely sufficient on its own once you become resident or acquire assets there.

Portuguese civil law places mandatory protections around family inheritance that cannot be ignored. If your estate plan does not account for those rules, it may not deliver the outcome you expect.

Cross border succession is not about documents in isolation. It is about legal systems interacting.

If you live, invest, or hold property in Portugal, your estate plan must be designed with that interaction in mind.

It may be worthwhile to consider putting a Portuguese will in place. Taking this step can help ensure that your arrangements in Portugal align with those made in the U.S. and can make the succession process in Portugal more straightforward for your chosen heirs. Support is necessary throughout the estate planning process to help keep everything coordinated and consistent across both jurisdictions.