What Is a Certificate of Coutume?

If your loved one owned assets in both the UK and France, your French notaire may ask you to provide something called a certificat de coutume.

For many UK families, this is one of the most confusing requests they receive during the French succession process.

A quick internet search often makes matters worse. Most of the results you’ll find relate to certificates required before marrying abroad, leading many people to think the notaire has asked for the wrong document.

In fact, they’re referring to something entirely different.

A certificat de coutume is a legal opinion explaining how the law of another country applies to a particular situation.

French notaires are experts in French law, but they cannot be expected to know the detail of every foreign legal system. Where a succession involves overseas assets or legal arrangements, they may ask for a specialist to explain how that country’s law works.

Rather than making assumptions about UK law, the notaire asks for evidence from someone qualified to explain it.

Why Might a Notaire Request One?

The request most commonly arises when the deceased owned assets outside France or had interests that don’t have a direct equivalent under French law.

One example is a UK trust.

Trusts are a familiar part of English and Welsh law, but they are largely unknown in French civil law. As a result, the notaire needs to understand exactly what rights the deceased had.

Depending on the trust, they may need clarification on questions such as:

Did the deceased own the trust capital?
Were they only entitled to receive income?
Who owns the trust assets?
Who has authority to sell trust property?
Who are the capital beneficiaries?
Do the trust assets form part of the deceased’s estate?

The answers to these questions can have a significant impact on how the French succession is administered and whether French inheritance tax applies.

The Problem for UK Families

Here’s where things become confusing.

Unlike some other countries, the UK does not have an official government-issued certificate of coutume.

There is no government department you can contact to request one.

There is no standard form.

There is no official register.

This often comes as a surprise to French notaires, who may regularly receive such certificates from other jurisdictions.

So What Do You Provide Instead?

In practice, UK families will often provide a legal opinion or declaration from the solicitor dealing with the relevant UK assets.

Rather than issuing a document called a certificat de coutume, the solicitor explains the relevant points of UK law and how they apply to the particular trust or estate.

This might confirm, for example, that:

the deceased had only a life interest in the trust;
they never became entitled to the trust capital;
the trust capital belongs to the capital beneficiaries; and
the trustees or beneficiaries—not the deceased—have authority over the trust assets.

For many French notaires, this provides the information they require, even though it isn’t formally called a certificat de coutume.

In Our Case

Our notaire requested a certificat de coutume in relation to UK trusts.

Initially this caused a great deal of confusion because, after searching online, everything we found related to marriage certificates rather than inheritance.

After discussing the matter with our UK solicitor, it became clear that no such official certificate exists in the UK. Instead, our solicitor prepared a formal declaration explaining how the trusts operated under UK law, the deceased’s rights during his lifetime, and who was entitled to the trust assets after his death.

That document was accepted as the practical equivalent.

Don’t Panic If You’re Asked for One

If your French notaire requests a certificat de coutume, don’t assume you’ve overlooked an official UK document.

In many UK successions, particularly where trusts are involved, the solution is simply to obtain an appropriate legal opinion from the solicitor acting on the UK side of the estate.

The important thing isn’t the title of the document—it’s ensuring the French notaire has enough information to understand how UK law applies to the assets in question.

What Is a Certificate of Coutume?