This is where one is accustomed to live irrespective of the frequency and duration. However, it is accepted that occupancy of less than one month in the year cannot be considered as usual. A person lives here throughout the year or for part of the year. It may be a second home or accommodation occupied occasionally.
In the surveys conducted by the INSEE, it is the situation during the period of the survey that counts to qualify the usual place of residence: a dwelling in which a person no longer lives or into which they have not yet moved is not a usual place of residence.
Decree n°2003-485 of 5 June 2003 on the population census defines the official populations using the notion of usual place of residence. It gives it a different definition and states what is meant by usual place of residence for people living outside a household.