Paternity is legal fatherhood—and establishing it is one of the most important steps in the child support process. A man is generally presumed to be the father of children born to his wife during their marriage. For unmarried parents, the biological father does not have a legal obligation to pay child support until paternity is established. Paternity may be established through a court-ordered paternity test, or by the father signing an acknowledgment of paternity (AOP).

In a case of mistaken paternity, a man who believes he is not the father of the child may file a petition (lawsuit), and the court may generally terminate the parent-child relationship and the man’s obligation to pay child support upon proof through genetic testing that he is not the father of the child.

And adding the father to the birth certificate is an important process related to paternity and child support. After paternity is established the father may be added to the child’s birth certificate—usually by filing a form with the state’s vital statistics office.

In Texas, paternity is crucial for determining legal fatherhood and has significant implications for child support. A man is presumed to be the father of a child if the child is born during his marriage to the mother. For unmarried parents, the biological father is not legally obligated to pay child support until paternity is established. Paternity can be established either by a court-ordered DNA test or by the father voluntarily signing an Acknowledgment of Paternity (AOP). If a man has reason to believe he is not the biological father of a child for whom he has been identified as the father, he can file a petition to challenge paternity. If genetic testing confirms he is not the father, the court may terminate the parent-child relationship and his obligation to pay child support. Once paternity is established, the father's name can be added to the birth certificate by filing the appropriate form with the Texas Vital Statistics Unit.