An international will is a will drafted and signed under a standardized format created by the 1973 Washington Convention so that its execution formalities are recognized across national borders. It is a narrower tool than its name suggests: it fixes only the question of whether the signing ceremony was valid, and it carries that cross-border weight only in the roughly thirteen countries that actually ratified the treaty. For anyone with assets in more than one country, that distinction decides whether an international will is the right centerpiece of an estate plan or merely one component of a larger strategy.
What an International Will Actually Is
The format comes from the Convention Providing a Uniform Law on the Form of an International Will, signed in Washington, D.C., on October 26, 1973.1United States Department of State. Convention Providing a Uniform Law on the Form of an International Will The treaty established a single set of signing and witnessing rules. A will following those rules is supposed to be accepted as formally valid in every ratifying country, regardless of the testator’s nationality, where the will was signed, or where the assets sit.
The practical reach is modest. According to UNIDROIT’s status report, only thirteen countries are full parties: Australia, Belgium, Bosnia-Herzegovina, Canada, Croatia, Cyprus, Ecuador, France, Italy, Libya, Niger, Portugal, and Slovenia.2UNIDROIT. Status – UNIDROIT The United States signed in 1973 and acts as depositary government, and a number of U.S. states have adopted the Uniform Probate Code provisions implementing the Convention domestically. The United Kingdom and Russia signed decades ago but never ratified.
This is the first thing to absorb before relying on an international will. If your overseas property sits in Germany, Japan, Mexico, or almost any country outside that short list, the international will carries no special status in that country’s courts. You still need a will that satisfies local formalities where those assets are located.
How You Execute One
The Uniform Law annexed to the Convention sets strict formalities. Miss one and the will loses its cross-border status, even if it might still function as an ordinary domestic will under local rules.
- The will must be in writing, but it can be in any language and produced by any method, whether handwritten, typed, or printed.
- The testator must declare in front of two witnesses and one “authorized person” that the document is their will and that they know its contents. The testator does not have to reveal what the will actually says.
- The testator signs the will (or acknowledges a signature already on it) in the presence of the two witnesses and the authorized person. All three then sign in the testator’s presence.
- If the will runs more than one page, every page must be numbered and signed by both the testator (or someone signing on the testator’s behalf) and the authorized person.
- If the testator physically cannot sign, the authorized person notes the reason on the will. Another person present may sign the testator’s name at the testator’s direction, with the authorized person documenting that as well.
These rules go further than what most U.S. states require for a standard will, where two witnesses without an authorized person are often enough. The extra layer is the whole point: the international will trades convenience for cross-border certainty.
The Authorized Person and the Certificate
Each ratifying country decides who qualifies as an authorized person. In U.S. states that adopted the relevant Uniform Probate Code provisions, that generally means attorneys licensed in the state. The Convention also lets countries authorize their diplomatic and consular officers abroad to supervise execution of international wills for their nationals.3UNIDROIT. International Will – UNIDROIT
After the signing, the authorized person completes a standardized certificate and attaches it to the will. The certificate confirms the testator’s identity, the identities of the witnesses, and that every required step was followed. The official date of the will is the date the authorized person signs the certificate. That certificate is what gives the international will its cross-border power; without it, or with gaps in it, the document is just an ordinary testamentary writing.3UNIDROIT. International Will – UNIDROIT
What It Does Not Do
The international will solves one problem: formal validity. It ensures the signing ceremony itself will not be rejected across borders. It does not touch substantive inheritance law. It has no effect on who is legally entitled to inherit, what share they receive, whether the testator had mental capacity, or how estate taxes are calculated. Those questions are decided by whichever country’s law applies to the specific assets or heirs.
The common misunderstanding is that because an international will is “valid,” its instructions will be carried out as written. A will can be formally perfect and still have its distribution wishes overridden by local inheritance rules. Two situations drive this home.
Real Estate Follows Local Law
Nearly every legal system applies the principle that real estate is governed by the law of the country where it sits. Own an apartment in France, and French law decides how that apartment passes at death, regardless of your nationality, your residence, or where your will was signed. Your international will’s formal validity is recognized, but its substantive instructions about who gets the apartment are subject to French inheritance rules. This is why estate planners frequently recommend a separate, locally compliant will for foreign real property.
Forced Heirship Can Override Your Choices
Much of continental Europe, Latin America, and parts of Asia operate under forced heirship regimes that reserve a mandatory share of the estate for close family members, typically children and sometimes spouses. These rules directly limit what any will can do, and formal validity does not override them.
The reserved shares are large. In France, one child is entitled to half the estate, two children to two-thirds, and three or more children to three-quarters. Belgium, after its 2018 reform, consistently reserves half the estate for children regardless of how many there are. Italy reserves between half and two-thirds depending on the number of children. If you are a U.S. citizen used to full testamentary freedom and you try to disinherit a child while owning property in one of these countries, the international will’s formal compliance does not help you. The local court will apply forced heirship rules to the assets within its jurisdiction. Louisiana is the only U.S. state with its own forced heirship system, protecting children under 24 and permanently incapacitated adult children.
Brussels IV May Matter More for European Assets
For assets in EU member states (except Denmark and Ireland, which opted out), the EU Succession Regulation, often called Brussels IV, is arguably more useful than the Washington Convention. It sets a unified choice-of-law framework: by default, the law of your habitual residence at death governs your entire succession, including real property in other EU countries.
Brussels IV also lets you elect in your will that the law of your nationality should apply instead. For a U.S. or U.K. national with property in France or Spain, that election can replace local forced heirship rules with the full testamentary freedom available under English or American law. The regulation determines only which succession law applies and who inherits; it does not address taxation. For EU-situated assets, a carefully drafted choice-of-law clause often does more practical work than the international will’s formal standardization.
One Will or Several
Whether to use one international will covering everything or create separate wills for different countries is one of the most consequential decisions in cross-border planning. Neither approach is universally better.
A single international will works well when your foreign assets are primarily financial accounts, investments, or other movable property in countries that ratified the Convention. The standardized format simplifies probate, and movable assets are generally governed by the law of your domicile rather than the country where the account happens to sit.
Multiple wills become the safer choice when you own real estate abroad, when any assets sit in countries outside the Convention, or when forced heirship rules require provisions drafted to local law. A locally drafted will prepared by an attorney in the country where the real estate sits can navigate registration requirements, language expectations, and substantive inheritance rules more effectively than a single international will trying to do everything from a distance.
The danger with multiple wills is accidental revocation. A new will executed in Country B with a standard “I revoke all prior wills” clause may destroy the will you carefully drafted for Country A. Each will must limit its scope to assets in a particular jurisdiction and include a carve-out confirming it does not revoke wills governing property elsewhere. Sloppy drafting is where most multi-will strategies fall apart.
What Happens After Death
Even with a flawless international will, you are likely to face ancillary probate when assets sit in a country different from where the primary estate is administered. Ancillary probate is the process of getting a foreign court or land registry to recognize the executor’s authority and transfer local assets according to the will.
For real estate it is almost always required. The country where the property sits will insist on its own proceedings before title changes hands. The process typically requires authenticated or apostilled copies of the will, the death certificate, proof of the executor’s appointment, and often certified translations. Local counsel handles the filing in the foreign jurisdiction.
The international will’s certificate can streamline this in Convention countries because the certificate serves as built-in proof that the will’s formalities are in order. In non-Convention countries, the executor goes through standard authentication, which can involve consular legalization or an apostille under the Hague Apostille Convention, depending on the country. Ancillary probate often takes months and requires hiring local attorneys in each jurisdiction.
Storage and Registration
After execution, the authorized person keeps a copy of the certificate and provides the testator with one. The certificate form includes an optional section where the authorized person can note the testator’s wishes for safekeeping. Many jurisdictions maintain will registries that record a document’s existence and location without storing the will itself. Registration is separate from execution and does not affect validity, but it solves a practical problem: making sure the executor can actually find the document.
If you have multiple wills in different countries, keep a master list showing each will, its date, the jurisdiction it covers, the attorney or authorized person who supervised execution, and where the original is stored. Give copies to your executor and at least one trusted family member. Estates get tangled in conflicting proceedings when wills are scattered and no one knows the full picture.
Changing or Revoking One
An international will follows the ordinary revocation rules of the jurisdiction where it was executed.3UNIDROIT. International Will – UNIDROIT Tearing up a copy or crossing out a provision is not enough in most jurisdictions.
To change specific provisions, you execute a codicil that itself complies with the international will formalities: two witnesses, an authorized person, and a new certificate. To revoke the will entirely, you execute a new will with a clear revocation clause. When several wills govern assets in different countries, the revocation clause has to be surgical. It should revoke only the specific prior will you intend to replace, identified by date and jurisdiction, and expressly leave wills covering other jurisdictions in effect. A blanket “I revoke all prior wills” in a new document is the fastest way to undo years of careful cross-border planning.