International Estate Planning: A Practical Guide for Assets in Multiple Countries

Why Domestic Estate Planning Falls Short

A will drafted by a US attorney covers US assets under US law. The moment the estate includes a London flat, a bank account in Switzerland, or inherited land in India, that single will enters territory it was never designed to handle.

Countries use different conflict-of-law rules. Common-law systems often apply the law of the property's location to real estate, while civil-law systems may apply one law to the entire succession based on the deceased's nationality or last habitual residence. Without deliberate cross-border planning, you leave your executor to untangle conflicting legal systems under deadline pressure, while grieving.

International estate planning is the work of making sure those systems do not collide at the worst possible moment.

The Core Problem: Conflicting Legal Systems

Common law countries (the US, UK, Australia, Canada) split the estate by asset type. Real property follows the law where it is located. Movable assets — bank accounts, investments, personal property — follow the law of the deceased's last domicile. This principle is called scission.

Civil law countries (France, Germany, Spain, Italy, and most of Continental Europe) take the opposite approach. Under the unity-of-succession doctrine, a single law governs the entire worldwide estate, typically based on the deceased's nationality or habitual residence.

These two approaches directly conflict when a person dies with assets in both systems. The UK court says French real estate follows French law. The French notary says the entire estate follows the law of habitual residence — which may be the UK. Each jurisdiction asserts its own claim, and neither defers to the other.

Five Steps That Actually Matter

1. Understand where your assets create legal exposure. Map each asset under the relevant rule: common-law systems generally apply situs law to real estate and domicile law to movable assets; for US estate-tax situs, stock issued by US corporations remains US-situs even when held through a foreign brokerage.

2. Decide whether you need one will or several. A single will governing worldwide assets is simpler but creates problems when a foreign court needs to probate your estate. Some countries require the original will — and handing the original to a French notary means the US probate court cannot proceed. Separate wills for each jurisdiction solve this, but they must be carefully coordinated so one does not accidentally revoke the other.

3. Make a choice-of-law election if you qualify. Under the EU's Brussels IV regulation, a testator can elect the law of their nationality to govern the succession. An American living in Germany can elect US law, preserving testamentary freedom over assets that would otherwise be subject to German forced heirship. But the election must be explicit in the will — it does not happen automatically.

4. Structure ownership to avoid ancillary probate. Real property held in your own name may require a local probate proceeding in a common-law jurisdiction, while civil-law systems often use a local succession process through notaries. Holding foreign real estate through a trust, a local company, or a joint tenancy can eliminate or reduce the need for ancillary probate. Each approach has its own tax and compliance trade-offs.

5. Address the tax exposure now. The US generally taxes citizens and tax residents on worldwide income and has bilateral estate tax treaties with 16 countries. A non-resident non-citizen dying with US-situs assets exceeding just $60,000 faces federal estate tax — a threshold so low that a modest stock portfolio triggers a filing. Treaty provisions can raise this dramatically through a prorated unified credit, but only if the estate claims them properly.

The Treaty Advantage Most People Miss

The US has active estate tax treaties with 16 countries: Australia, Austria, Canada, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Japan, Netherlands, Norway, South Africa, Switzerland, and the UK. These treaties do not just prevent double taxation — they can dramatically reduce the tax bill.

The most powerful provision is the prorated unified credit. Under several modern treaties (UK, Canada, Germany, France), a non-resident non-citizen's estate can claim a share of the full US credit proportional to the ratio of US assets to worldwide assets. For decedents dying in 2026, the basic credit amount is $5,945,800, corresponding to a $15 million basic exclusion. If US-situs assets represent 10% of the worldwide estate, the estate gets 10% of the full credit — potentially sheltering millions in assets that would otherwise be taxed at rates up to 40%.

Claiming this credit requires filing Form 706-NA with a Treaty-Based Return Position Disclosure (Form 8833). Many executors do not know these treaty benefits exist, and the IRS does not volunteer them.

When to Get Professional Help

International estate planning is one area where DIY approaches create real risk. If you hold real property in a foreign country, have changed your country of residence, or are a non-US citizen with US investments, working with an attorney who specializes in cross-border estates is worth the investment.

The key qualifier: your attorney should hold a Trust and Estate Practitioner (TEP) designation from STEP (the Society of Trust and Estate Practitioners) or demonstrate specific cross-border experience. A domestic estate attorney who has never dealt with ancillary probate, foreign forced heirship, or bilateral tax treaties is unlikely to spot the issues that matter.

If you are already managing an international estate after a death — rather than planning ahead — the International Estate toolkit provides the structured checklists, document authentication workflows, and tax filing guides that keep parallel proceedings on track across multiple jurisdictions.