How Is Paternity Established in Illinois?

 Posted on June 23, 2026 in Child Custody

If you and your child's other parent were never married, the law does not automatically recognize paternity, the father-child relationship. In Illinois, unmarried parents must take specific legal steps to establish it.

According to the Centers for Disease Control and Prevention, 40 percent of all U.S. births in 2023 were to unmarried women. That means about 1.4 million U.S. births in 2023 involved unmarried parents, leaving many families with important questions about establishing paternity and each parent's legal rights and responsibilities. Without established paternity, a father has no enforceable right to parenting time, and a mother has no legal basis to seek child support.

A Wheaton, IL paternity attorney can explain your options in 2026 and help you take the right legal steps for your family.

What Legal Paternity Means for Unmarried Parents in Illinois

When a child is born to married parents, Illinois law presumes the husband is the legal father. However, that rule does not apply to unmarried parents. Under the Illinois Parentage Act of 2015, 750 ILCS 46/, an unmarried father has no automatic legal rights to his child until paternity is formally established.

Legal paternity gives a father the right to request parenting time and a role in decisions about the child's life. It also gives the child access to financial support and health insurance through the father, as well as inheritance rights. If the father has a military pension or government benefits, paternity must be in place for the child to qualify.

A mother faces the same barrier. Without a legal finding of paternity, she cannot obtain a court order requiring the father to pay child support. That means no enforcement mechanism, no wage withholding, and no legal recourse if he stops contributing.

What Is a Voluntary Acknowledgment of Parentage in Illinois?

The most common way to establish paternity in Illinois is through a Voluntary Acknowledgment of Parentage, or VAP. This is a legal form that both parents sign, usually at the hospital after a child is born. It can also be completed later through the Illinois Department of Healthcare and Family Services.

Once a VAP is signed and filed, it has the same legal effect as a court order. Before signing, both parents should understand what they are agreeing to. The father is accepting all the legal rights and duties that come with being a parent, including the potential obligation to pay child support and the right to seek parenting time.

A VAP can usually be cancelled within 60 days after it takes effect, or before a court or administrative case involving the child begins, whichever happens first. After that, withdrawing requires going to court and proving fraud, duress, or a material mistake of fact. That is a difficult standard to meet, so both parents should consider the decision seriously before signing a VAP.

How Do Illinois Courts Establish Paternity Through DNA Testing?

When parents disagree about who the father is, or when one party will not sign a VAP, either parent or the state can file a paternity action in court. The Illinois Parentage Act allows courts to order genetic testing to determine biological parentage.

DNA testing is highly accurate. If the results confirm paternity, the court enters an order legally establishing the father-child relationship. The court can also address child support, parenting time, and the allocation of parental responsibilities.

Some cases involve challenging an existing presumption of paternity. For example, a man may believe he is not the biological father of a child born during a marriage. Under the Illinois Parentage Act, a petition to challenge paternity in these circumstances generally must be filed within two years of learning facts suggesting the presumed father is not the biological father.

What Parenting Rights and Support Look Like After Paternity Is Set

Once paternity is in place, either parent can ask the court to set a parenting plan. Illinois courts base parenting time and decision-making on the best interests of the child. Judges consider each parent's relationship with the child, the child's home and school situation, and how willing each parent is to support the other's involvement.

Child support is calculated under the income-sharing model in Illinois. The court looks at both parents' incomes and the time each parent spends with the child. Without established paternity, there is no legal foundation for a support order at all.

Contact a Wheaton, IL Paternity Attorney Today

Paternity cases range from simple to highly contested, and the outcome has lasting effects on your rights and your child's future. With over 45 years of combined legal experience, the attorneys at Smit Zaruba P.C. are ready to fight for you and your child. Contact a Kane County, IL family law lawyer at Smit Zaruba P.C. to schedule a consultation. Call 630-480-7600 today.