Siège social is a concept in international law

International law

Public international law concerns the structure and conduct of sovereign states; analogous entities, such as the Holy See; and intergovernmental organizations. To a lesser degree, international law also may affect multinational corporations and individuals, an impact increasingly evolving beyond...

 for determining the nationality

Nationality

Nationality is membership of a nation or sovereign state, usually determined by their citizenship, but sometimes by ethnicity or place of residence, or based on their sense of national identity....

 of companies

Company

A company is a form of business organization. It is an association or collection of individual real persons and/or other companies, who each provide some form of capital. This group has a common purpose or focus and an aim of gaining profits. This collection, group or association of persons can be...

. It is essentially based on effective nationality as opposed to “paper nationality”. The paper nationality is where the company has been incorporated, but the effective nationality requires a genuine link to the corporate activity. It describes the nationality based on the location of the actual activity of the corporation through where the owners are or the actual business is done.

According to the criterion of siège social, siège réel or siege réel social, a company's nationality derives from “the place where the legal entity's judicial and economic integration is situated”, or in other words the company's principal place of establishment.