Cal. Fam. Code § 3024

In making an order for custody, if the court does not consider it inappropriate, the court may specify that a parent shall notify the other parent if the parent plans to change the residence of the child for more than 30 days, unless there is prior written agreement to the removal. The notice shall be given before the contemplated move, by mail, return receipt requested, postage prepaid, to the last known address of the parent to be notified. A copy of the notice shall also be sent to that parent’s counsel of record. To the extent feasible, the notice shall be provided within a minimum of 45 days before the proposed change of residence so as to allow time for mediation of a new agreement concerning custody. This section does not affect orders made before January 1, 1989.