Setting up a business in France (as opposed to being self-employed, see related articles) can often result from the extension of a business activity already undertaken in your home country, and that can be gradually developed in France. There are three main stages in creating a business presence in France by an existing UK company:
Bureau de liaison
You can operate in France as a 'bureau de liasion' which is basically an office designed to research the local French market, establish contacts, undertake advertising and promotion, and do all things necessary to prepare for an eventual commercial activity in France. Provided it is limited to these activities, no formal registration is generally required. You may ask your local French chamber of Commerce (CFE) to register your bureau de liaison but they are not obliged to do so. If they accede to your request, you will be issued with a business registration number (SIREN, SIRET) and a business registration document (K-bis) - all of which may assist your contacts with official bodies (including opening a local bank account) and public organisations to which you intend to market your product or services. The bureau de liaison has a limited life as you must register a formal branch office or subsidiary once you start actively trading in France.
Branch office ("succursale")
The branch office is essentially an extension of the parent company, and while it has a certain autonomy and may sign contracts, receive payments etc locally, on behalf of the parent company, it remains under the control of the parent. Formal registration with the CFE is required and the branch office will receive its SIREN, SIRET and K-bis. Its fiscal status will be subject to French rules of taxation for branch offices, including repatriation of profits, and matters covered under dual taxation agreements between, say, Britain and France. Registration is required within 15 days of establishment.
Sudsidiary company ("filliale")
This is basically a French company which is wholly or partly owned by the parent company, and set up using one of the French equivalents of the limited liability company, such as an SA or SARL. It is subject to French taxation and other regulations applicable to French companies.
Registration and documents required
For all the above registrations, documents required include copies of the company statutes (Memorandum and Articles of Association), a copy of the board's decision to open a French office, personal details of those responsible for the French office - all of which have to be translated into French by a sworn translator ("traducteur assermenté"). The subsidiary will require the setting-up a French SA or SARL using French forms of statutes, either prepared by a lawyer or using standard models.
Annual returns
None are required for the bureau de liasion (as it does not trade), but are required in the case of the branch office (in addition to the authorities in the home country). The French subsidiary is treated as a normal French company.
Management and employees
The status of the manager or "gérant" of the bureau de liaison or branch office will depend if he/she is a (temporary) expat or resident in France for tax and social security purposes, in the latter case complying with French requirements. The subsidiary comes wholly under French rules, as do (French) employees in all three cases, for purposes of tax and social security and terms of employment.
Further information
Very helpful advice and information including printed fact sheets from the Commercial Attaché of the French Embassy in London about how to establish a presence in France, and from the French Chamber of Commerce in London. In France, from your local CFE and the British Chamber of Commerce in Paris.