About us
In France and abroad, Cossé Probate Genealogy Office works with rigour and passion.
Cossé Probate Genealogy Office is a French simplified joint-stock company (SASU) founded in 2017, specialising in probate and property genealogy. It has offices in Rouen and in Remire-Montjoly (French Guiana).
The firm is headed by Nicolas Cossé, who holds a dual bachelor’s degree in law and foreign languages, as well as a professional bachelor’s degree in probate genealogy.
In 2020, he began research in French Guiana as part of a public tender and gradually became an expert in complex joint-ownership cases in the French overseas territories.
In 2025, he was appointed Expert and Representative of Généalogistes de France in French Guiana and to the Archives of the French Ministry for the Overseas Territories.
Today, the firm is the leading reference for the overseas territories within Généalogistes de France.
Joint ownership in the French overseas territories
In the French overseas departments and territories, many properties have remained in joint ownership for several generations: because estates were not settled after each death, a single plot of land may now belong to dozens or even hundreds of heirs, scattered across the overseas territories, mainland France and abroad. These situations prevent any sale, division or development of the land, and weigh heavily on families and local authorities alike. Untangling them can mean going back as far as the 19th century, cross-referencing often incomplete local civil registers, mortgage registers, notarial records and the collections of the French National Overseas Archives (ANOM). Since 2020, the Étude Généalogique Cossé has specialised in these cases: it identifies and traces every rightful heir, establishes a reliable line of succession and supports notaries, families and municipalities through to the end of joint ownership, notably under the French law of 27 December 2018, known as the “Letchimy law”, which makes it easier to settle such estates.
International estates
Thanks to our knowledge of common law and our network of correspondents around the world, we help notaries and other genealogists settle international estates: locating a person, obtaining a document (civil records, will, probate, etc.), searching for heirs or assets, or information on the law in force in a country.
Today, nearly half of our cases are exclusively international, and nearly three quarters have an international dimension (birth, marriage or residence of an heir abroad, for example).
Member of
CGPChambre des Généalogistes Professionnels, the first association of European genealogists, bringing together family and probate genealogists.
Généalogistes de FranceThe national body representing genealogy professionals in France, which defends and represents the profession.
APGAssociation of Professional Genealogists, the world’s largest association of professional genealogists.
A case to entrust to us?
Call us or write to us: we reply quickly, whether you are in France or abroad.