When a child is born to parents who are not married to each other in Oklahoma, the question of whose last name does a baby get is common. While many people believe there is an automatic rule, the reality is that the decision depends almost entirely on the agreement between the parents and the legal steps taken at the time of birth.
Here is a breakdown of how Oklahoma law handles the naming of a child born outside of marriage as of 2026.
The Default: The Mother’s Choice
In Oklahoma, when a mother is unmarried at the time of birth, she is presumed to have sole legal custody of the child by default. Consequently, she generally has the initial authority to choose the child’s name for the birth certificate.
- If the father is not present or not acknowledged: The baby will typically take the mother’s last name.
- The Mother’s Prerogative: The mother can choose to give the baby her last name, the father’s last name, or a hyphenated version of both.
Adding the Father’s Last Name
For the father’s last name to be placed on the birth certificate, paternity must be legally established. Under Oklahoma Statute Title 63, § 1-311, the father’s name will only be entered on the birth certificate if:
- Acknowledgment of Paternity (AOP): Both parents sign a voluntary AOP form (usually at the hospital). By signing this, both parents agree on the biological paternity and the child’s name.
- Court Order: A judge issues an order establishing paternity and directing the name to be entered or changed.
What Happens if the Parents Disagree?
If the parents cannot agree on a last name at the hospital, the mother’s choice typically prevails on the initial birth certificate. However, the father has the right to file a Paternity Action in court.
In these cases, an Oklahoma judge will decide the child’s last name based on the “Best Interests of the Child.” A judge is not required to give the child the father’s name just because paternity is proven.
Factors a judge may consider include:
- The length of time the child has used a particular name.
- The potential impact on the child’s relationship with each parent.
- The child’s identification with a particular family unit.
- Any social or medical reasons for a specific name.
Changing the Last Name Later
If the child was originally given the mother’s last name and the parents later decide to change it (or the father successfully petitions for a change), the process involves filing a Petition for Change of Name of a Minor in the District Court.
- Mutual Consent: If both parents agree, the process is straightforward.
- Contested Change: If one parent objects, the court will hold a hearing to determine if the change serves the child’s best interests.
- Notice Requirement: Even if you are the primary custodial parent, you generally cannot change a child’s last name without giving formal legal notice to the other parent, provided their paternity has been established.
Summary for Unmarried Parents
- At the Hospital: The parents can agree to any name (Mother’s, Father’s, or Hyphenated) as long as an Acknowledgment of Paternity is signed.
- Without an AOP: The child typically takes the mother’s last name, and the father’s name is left off the birth certificate.
- In Dispute: The court has the final say based on what is best for the child’s identity and well-being.
Tulsa Paternity Lawyers Near You
Are you involved in a disagreement over what last name a baby gets if they are born to unwed parents? Our Tulsa paternity lawyers can help. If your child’s last name needs to be changed or you need to establish paternity to protect your parental rights, we can help. For a free consultation with a paternity and custody lawyer at Tulsa Divorce Attorneys and Associates, call 539.302.0303. Or if you like, follow this link to ask an online legal question.