Can an Unwed Father Change His Child’s Last Name to His in an Oklahoma Paternity Case?

One common question in family law is whether an unmarried father can change his child’s last name so it matches his surname. In Oklahoma, the short answer is yes — but only under specific legal conditions and through the court system.

First, Establishing Paternity Is the First Step

Before a father can seek to change a child’s surname, he generally must first be recognized as the legal father of the child. For children born out of wedlock, this often involves one of two methods:

• Voluntary acknowledgment of paternity: Both parents sign a sworn form acknowledging that the man is the father, which then gets filed with the Oklahoma State Department of Health. Once that is done, the father’s name may be added to the child’s birth certificate.
• Court-ordered paternity determination: If the parents do not agree, the father (or the mother) can file a paternity action in court. DNA testing is typically used and, if the test confirms paternity, the judge will issue an order adjudicating the father as the child’s legal parent.

Only after paternity has been legally established — either administratively or by the court — can the father move forward with a request to change the child’s last name.

Filing a Motion to Change the Child’s Surname

Once paternity is established, Oklahoma law lets any party with legal standing — including the father — file a motion in court to change a child’s surname to that of the father. This process is outlined in Title 10, Section 90.4 of the Oklahoma Statutes.

Here’s how it works:

• File the motion: The father (or another party like the mother, custodian, or legal guardian) files a petition with the court requesting that the child’s surname be changed.
• Service and notice: The court sets a hearing date, and all parties — including the other parent — must be served with notice of the hearing.
• Best interest of the child: At the hearing, the judge will consider evidence and arguments from both sides. Importantly, the court must find that giving the child the father’s surname is in the child’s best interest before issuing an order.

Agreement Between Parents

If both the mother and father agree to the name change, the process is often smoother. Many statutes and practice resources note that when both parents consent, the judge can simply enter an order approving the surname change without a contested hearing.

Once the court issues a name-change order, the State Department of Health’s Division of Vital Records will amend the child’s birth certificate to reflect the new surname.

What If the Mother Objects?

If the mother does not agree, the father can still pursue the name change, but the case becomes contested. In contested situations:

• The court will hold a hearing after proper notice. At this hearing, mothers and fathers are presumed to have the same rights.
• The judge looks at factors such as the effect on the child’s relationships, stability, and identity to decide whether the name change is appropriate.
• Oklahoma appellate cases have recognized that courts have broad discretion here, and name changes can be granted over objection if the father has established paternity and the judge finds the change serves the child’s best interest.

Practical Tips for Unwed Fathers

• Get paternity established first — this is a prerequisite for most legal actions involving parental rights, including a name change.
• Be prepared for a hearing — especially if the mother disagrees. Evidence about the child’s best interests matters.
• Work with an attorney experienced in family law — navigating contested hearings and proving “best interest of the child” can be legally complex.

Tulsa Paternity Lawyers In Your Corner

An unwed father in Oklahoma can pursue changing his child’s last name to his own, but he must first establish paternity and then file a court motion. If both parents agree, the process is straightforward; if not, the court will decide based on what is best for the child. For a free and meaningful consultation with a child custody and paternity attorney at Kania Law Office, call 918.743.2233. Or you can ask a lawyer a free online legal question by following this link.