If both parents agree to a name change for a child under 18, you apply to the appropriate county court by filing a Petition for a Change of Name. As the California Courts website explains, it's then a simple matter to publish a legally required notice in a newspaper -- the court will give you instructions for doing so. If you file for a name change by yourself, you must notify the other parent. If there is no objection from the other parent, the court will grant the requested name change.
Contested Name Change
After you file your application, the court will give you a court date for a hearing. As of the date of publication, the date of the hearing was about 6 to 12 weeks after filing. If you filed the application by yourself, you must give notice to the other parent at least 30 days before the hearing. If the other parent opposes the name change, the judge at the hearing will determine if changing your child's name is in his best interest. An older child's wishes will be factored into the judge's decision.
If the court approves your child's name change, buy enough certified copies of the official document from the court. The document, which is called the Decree Changing Name, will enable you to change documents like your child's Social Security card, birth certificate, passport, school records and immigration records. If your child is of driving age, use a certified copy of the Decree Changing Name at the DMV to change the name on his driver's license. Changing a Social Security card can be done at a local Social Security office.
If you are changing your name and your child's name due to domestic violence, the court system can help keep your new name confidential. By registering with the Safe Home program, your new name and your child's new name will not appear on court records. You can ask a local domestic violence center, family law facilitator or the victim services unit in the local district attorney's office for assistance with the registration process.