How Is Paternity Established in Illinois?

 Posted on September 29, 2026 in Paternity

Paternity is an important legal status that can give a child inheritance rights and provide a path to child support. Until parentage is legally established, a father might not be able to ask the court for parenting time or other parental rights.

Illinois gives parents several ways to establish paternity. Which one is used depends on the situation.

A Kane County, IL paternity lawyer can help you take the correct legal steps to establish paternity in 2026.

Why Does Establishing Paternity Matter in Illinois?

Establishing paternity makes a father the child’s legal parent, with the rights and duties that come with that. For the child, paternity can open the door to:

• Child support from both parents
• Health insurance through either parent’s plan
• Inheritance rights
• Social Security or veterans’ benefits through the father
• Access to the father’s family medical history

Once paternity is established, the child’s birth certificate can also be updated to list the father.

For a father, legal parentage is usually the first step toward asking a court for parental responsibilities and parenting time. Without it, a biological father usually cannot ask the court for either, even if he is very involved in the child’s life.

How Is Paternity Established in Illinois?

The Illinois Parentage Act of 2015 sets out several ways to establish a legal parent-child relationship. Which one applies depends on whether the parents were married and whether they are in agreement about establishing paternity.

Presumption Through Marriage or Civil Union

People who are married are both presumed to be the parents when the child is born within the marriage or civil union. This presumption also applies to a child born within 300 days after the marriage or civil union ends, or after a legal separation (750 ILCS 46/204). A person can also be presumed to be a parent if they get married after the child is born and agree in writing to be named on the birth certificate.

Voluntary Acknowledgment of Paternity

Under 750 ILCS 46/301, unmarried parents who agree on paternity can sign a document called a Voluntary Acknowledgment of Paternity (VAP). Many parents sign it at the hospital after the birth, but it can be signed and witnessed later as well.

Once it’s filed with the Illinois Department of Healthcare and Family Services, a valid VAP has the same effect as a court judgment of parentage. It can also serve as the basis for a child support order without a separate case to prove paternity.

Administrative Paternity Through HFS

Parents who use the state’s child support services may be able to establish paternity through the Illinois Department of Healthcare and Family Services instead of a courtroom. The department can handle both uncontested and contested cases, including cases that need genetic testing.

Court Order and Genetic Testing

When a parent disputes paternity or won’t cooperate, either parent can ask the court to declare parentage through a court order. The court can order the mother, the child, or the alleged father to take a DNA test. If the results show at least a 99.9% probability of parentage, the alleged father is presumed to be the parent (750 ILCS 46/404).

Establishing paternity through a court order can be especially important if child support is needed but not being paid.

Can a Voluntary Acknowledgment of Paternity Be Undone in Illinois?

A VAP can be rescinded, but the window is short. A signer can file a rescission within 60 days after the acknowledgment takes effect unless a court or administrative case involving the child begins first.

Once this period has passed, challenging paternity is much harder. The signer must prove that there was fraud, duress, or a material mistake of fact at the time of signing by clear and convincing evidence. This challenge must typically be filed within two years of the VAP taking effect. Child support generally continues while a challenge is pending.

If you have doubts about whether you’re the father of a child, it might be worth asking for a DNA test before you sign.

Is There a Deadline to Establish Paternity in Illinois?

If a child has no presumed, acknowledged, or court-declared parent, a case to establish parentage can generally be brought at any time. A presumed parent’s status works differently. A person seeking to challenge presumed parentage usually must file within two years after learning the relevant facts. Waiting can still have costs, though. Records get harder to find, and a father who hasn’t been involved may have a harder time asking for parenting time later.

Call a St. Charles, IL Paternity Lawyer Today

Whether you’re a mother seeking support or a father who wants a role in your child’s life, establishing paternity is the place to start. Our Kane County, IL parentage attorneys can walk you through whichever process is appropriate for your situation.

Our main attorney is a trained mediator with significant family law experience. Our firm focuses on mediation when possible, but we’re prepared to litigate aggressively if a case needs to go to court.

Call Shaw Sanders, P.C. at 630-584-5550 to schedule your free consultation.