How to Change a Child's Last Name

The legal process for changing a child’s name to his biological father’s last name is not as simple as amending a birth certificate, Social Security card or other official document, according to Gayle R. Rosenblum, a New York family law attorney.

“For the most part, changing a child’s name to his biological father’s last name is on consent of both parents after paternity has been established.” Usually, the process is not too involved if the child’s mother consents to the name change. However, the specifics of the method for changing a child’s name to that of the biological father can vary from state to state.

Use the Acknowledgement of Paternity (AOP) form to change your child’s name if you and the child’s father were never married or did not marry until after your child was born. In some states, the Acknowledgement of Paternity form must also be completed to add the biological father’s name to the birth certificate of a child born to parents who were divorced for more than 10 months at the time of the child’s birth. The American Pregnancy Association points out that in most states, if a woman is not married in the last 300 days before her baby is born, no father is listed on the birth certificate until both biological parents sign the AOP. Although the actual title of the form may differ depending on the state, this is the form that must be completed when both parents agree to the paternity of a child.

Establish paternity, as you may need to change your child’s last name through the Family Court. In cases where paternity of a child is uncertain, the court may offer genetic testing to prove who is the child's father. According to, in the state of New York, you can only change the last name of your child through Family Court if a paternity case has established who the child’s biological father is. Once it is proven who the father is through a court action, you then have the right to change the child’s name if both of you agree. Most states require that you petition the court to legally change a child's last name. The parents are required to sign the appropriate forms, which vary by state, but forms usually include the petition for a name change, court order approving the name change and final court decree authorizing the name change. In some cases, a petition giving public notice of the name change may be needed as well.

Ask the court to grant the child a name change. When both parents do not agree on changing the child’s name to that of the father, it then falls on the court to determine whether it is in the child’s best interest to grant the order. The decision is generally made as part of the establishment of paternity through the court. If the child’s name is not changed at that time, the parent requesting the name change must file a court petition to change the child’s name and request a hearing.

Petition the court. A father can petition the court to change his child’s last name if he is the biological father and the mother does not agree to the name change. The family court will consider what is best for the child, as well as how long he has had the other last name. Another consideration is whether a change of name would impact the child’s connection with his mother, siblings and other family members. If the father wins his case, there will then be a court order issued to change the name.

Update your child’s Social Security card once her last name on her birth certificate has been changed. Go online to the Social Security website or visit your local Social Security office for an application to update your child’s name. You will need to complete Form SS-5 and submit proof of your child’s name change. If her name was changed through a court order, you will also need to provide a copy of that order. Otherwise, you must present an official document showing your child’s new last name. In some cases, you may need to provide a document reflecting the child’s former last name as well.