Any stay in French territory for more then three months is considered as residency. To become a French resident you need a residency permit, with the exception of EU/EEA nationals for whom the residency permit is no longer mandatory.
However, even for EU-citizens a residence permit (carte de séjour)is very useful, as this makes life easier,and without one you cannot get access to many state services or aids - such as housing financial aid, etc.
Since 2009, long stay visa holders are allowed to stay in the country for up to 12 months, according to the purpose of their stay and the validity of their visa. However, if they intend to stay for more than six months, they need to register at the French Office of Immigration and Integration during the first three months of their stay.
Non-EU/EEA nationals. Unlike visas, residence permits are only issued in France. You apply in person at your local préfecture de Police or sous-préfecture in at the services des étrangers (foreigners office). If the prefecture is not close to your place of residence, you can also apply through your local town hall office (mairie). To make an application, you need to have obtained a long-stay visa before coming to France. A short-term visa is not sufficient to make an application for residency!
To obtain your residence permit, you have to submit many documents, which will depend on what kind of residence permit you are going to ask for. In many cases this will include the following:
If a document is not in French, you should supply a certified French translation.
On submitting all documents, you will receive a receipt acknowledging an application for a residence permit. This acts as the document legalizing your temporary stay in France until you get your permit (or not). The whole process takes from between a week to a few months.
A residence permit usually also gives the right to residency for your spouse and children (when minors).