If the parents are not married when a baby is born in Texas, the baby gets the mother’s last name by default. The father’s surname becomes an option only if both parents sign an Acknowledgment of Paternity (AOP), which legally establishes the father’s relationship to the child. Without that step, the state has no legal basis to put the father’s name on the birth certificate, and the mother’s surname is the only one available.
The Default Rule for Unmarried Parents
Texas treats the mother as the sole legal parent of a child born outside marriage until paternity is established. Because the father has no legal tie to the child yet, his name doesn’t appear on the birth certificate and his surname isn’t on the table. The child receives the mother’s last name.
The Texas Attorney General’s office states that children born to unmarried parents do not have the same established legal rights with their fathers as children born to married parents, and that paternity must be established before those rights exist.1Texas Office of the Attorney General. Paternity, Child Support and You Married parents don’t run into this because Texas presumes the husband is the father, so his surname is already available at birth.
How Signing an Acknowledgment of Paternity Changes the Surname Options
The fastest route to adding the father’s name — and his surname — to the birth certificate is the Acknowledgment of Paternity. Hospitals typically make the form available right after birth, and parents can also sign later through a certified entity or the Texas Attorney General’s office.
Both the mother and the father sign the AOP under penalty of perjury, confirming the man is the biological father.2State of Texas. Texas Family Code 160.302 – Execution of Acknowledgment of Paternity The form also requires the parents to state that no other man is presumed, acknowledged, or adjudicated as the father, and that both signers understand the AOP carries the same legal weight as a court order establishing paternity.
Once filed with the Texas Vital Statistics Unit, a valid AOP has the force of a court adjudication of paternity and gives the acknowledged father the full rights and duties of a parent.3State of Texas. Texas Family Code 160.305 – Effect of Acknowledgment or Denial of Paternity His name goes on the birth certificate, and the surname question opens up.
What Last Names Parents Can Choose
With a signed AOP, the parents can agree to give the child the father’s last name, the mother’s last name, or a hyphenated combination of both. The agreement has to be mutual, and the chosen surname goes on the birth certificate at the time it’s issued.
A verbal agreement by itself does nothing. If the parents agree on the father’s surname but don’t sign the AOP, the birth certificate still lists only the mother, and the baby still gets her last name. The paperwork has to be in place first.
When Parents Disagree About the Surname
If the parents can’t agree, the AOP process stops, because it needs both signatures. The birth certificate is then issued with the mother’s surname, and changing it requires going to court.
Suit to Adjudicate Parentage
Either parent can file a suit to adjudicate parentage, asking a judge to formally establish the father-child relationship. A name change for the child can be requested as part of that case. The court may order a name change on a showing of good cause, which the statute leaves to the judge’s discretion. If the resulting order differs from the existing birth record, the court directs the Vital Statistics Unit to issue an amended birth certificate.4Texas Constitution and Statutes. Texas Family Code 160.636 – Order Adjudicating Parentage; Costs
Standalone Name Change Petition
If paternity is already settled but the parents fall out over the surname later, either parent can file a petition to change the child’s name under Chapter 45 of the Texas Family Code. The petition is filed in the district court or county court at law in the county where the child lives, and a judge will grant it only if the change is in the child’s best interest.5Justia Law. Texas Family Code Chapter 45 – Change of Name
If the child is ten or older, the child’s written consent must be attached to the petition.6Justia Law. Texas Family Code 45.002 – Requirements of Petition The other parent must be formally served. Once a judge signs the order, it’s used to amend the birth certificate. Filing fees generally run a few hundred dollars, with the exact amount depending on the county.
If the AOP Is Rescinded, the Surname Reverts
An AOP isn’t locked in the moment it’s signed. Either parent who signed can rescind it within 60 days of its effective date, or before any court proceeding involving the child begins, whichever is earlier.7State of Texas. Texas Family Code 160.307 – Procedures for Rescission Rescission is done by filing a completed form with the Vital Statistics Unit under penalty of perjury and sending a copy by certified mail to the other signer.
After 60 days, the AOP can only be challenged by proving fraud, duress, or a material mistake of fact, and no challenge is permitted once a court has issued any order affecting the child, including a child support order.8Texas Constitution and Statutes. Texas Family Code 160.308 – Challenge After Expiration of Period for Rescission
A rescission that voids the AOP also removes the father’s name from the birth certificate. The child’s surname reverts to the mother’s last name unless a court orders something different.
A Note on What the Surname Doesn’t Decide
The last name on the birth certificate doesn’t determine the child’s legal rights. Inheritance from the father, eligibility for his benefits, and the father’s own ability to seek custody or visitation all depend on whether paternity has been legally established, not on whose surname the child carries.1Texas Office of the Attorney General. Paternity, Child Support and You A child with the mother’s surname and a signed AOP has the same legal relationship to the father as a child who carries his last name.