The father and mother share parental authority.
However, when filiation is established toward one of the parents, more than one year after the birth of the child whose affiliation is already established toward the other parent, the latter exercises alone parental authority.
Parental authority may, however, be exercised jointly in the event of a joint declaration by the father and mother before the Chief Registrar of the High Court or by a decision of the Family Judge. (Article 372 of the Civil Code)
Caution: The separation of parents has in principle no effect on the exercise of parental authority.
It is only in very special cases that the Family Judge may decide that parental authority will be exercised by one of the parents only.
The Family Judge can either:
Each parent contributes to the maintenance and upbringing of the children in proportion to his/her resources, those of the other parent, and the needs of the child. This obligation does not cease automatically when the child is of age (= over18). (Article 371-2 of the Civil Code)
A purely indicative table edited by the Ministry of Justice will allow you to obtain a rough estimate of your alimony.