Is There a Time Limit for Establishing Paternity in Illinois?

 Posted on September 28, 2026 in Paternity

Paternity can be established in Illinois years after a child is born. When a child has no other legal parent, a parentage case can be started at any time while the child is under 18. After the child turns 18, only the child can start the case. When another man is already presumed to be the father or when someone has signed a Voluntary Acknowledgment of Paternity, though, strict deadlines can apply.

A Cook County, IL paternity lawyer can explain which time limits may apply to your family in 2026.

When Is There No Deadline to Establish Paternity in Illinois?

Under the Illinois Parentage Act of 2015, a case to establish parentage for a child with no presumed, acknowledged, or adjudicated parent may be started at any time (750 ILCS 46/607). This means no other person is already legally recognized as the child’s parent through a legal presumption, a signed acknowledgment, or a court order. This often covers children born to unmarried parents if they didn't establish paternity.

Once the child becomes an adult (turns 18), only they can start paternity proceedings.

What Deadlines Apply to Establishing Paternity if Someone Else Is Presumed to Be the Father in Illinois?

Illinois presumes a person is a child's parent in certain situations. The most common is when a man is married to the mother when the child was born. That man is generally presumed to be the child’s father unless the presumption is legally challenged or a valid denial of parentage applies.

If another person wants to challenge that presumption of paternity, they must do so before the deadline. Under 750 ILCS 46/608, anyone other than the child usually must file within two years after they knew or should have known the relevant facts of the situation. These might include who a child's biological father is. It could also apply to a husband who learns he may not be the biological father.

If a person is under a legal disability or duress, or when the facts of the case were fraudulently concealed, that time may not count towards the two-year limit.

How Long Do You Have to Challenge a Voluntary Acknowledgment of Paternity in Illinois?

Many unmarried parents sign a Voluntary Acknowledgment of Parentage (VAP), which is the Illinois form used to establish legal paternity without going to court. This document establishes paternity as effectively as a court order.

A signer can cancel the VAP by filing a rescission with the Illinois Department of Healthcare and Family Services. This must be done within 60 days after the acknowledgment takes effect to be valid unless there is a court or administrative case involving the child. In this case, the court deadline is the start date instead.

After the 60-day window closes, challenging a VAP is much more difficult. A signer can challenge the acknowledgment only for fraud, duress, or a material mistake of fact. The challenge has to be filed within two years of the acknowledgment's effective date. The person challenging it must prove their case by clear and convincing evidence.

Does Waiting to Establish Paternity Affect Child Support in Illinois?

Waiting to establish paternity can affect child support. Current child support usually starts when the other parent is served with the case. A judge can also order support for a period before the case was filed. When deciding whether to do this, the judge can consider whether the parent knew about the child, whether they had helped support the child, whether support had been requested, why the case was delayed, and how the delay affected the parent.

Paternity is legally necessary for a court to order child support for a child. Establishing paternity is also the first step for a father who wants parenting time or a share of parental responsibilities.

Call a Skokie, IL Paternity Lawyer Today

Parentage deadlines depend on what exactly a parent or parents hope to achieve and what legal steps have already been taken in the case. If you're hoping to establish or challenge paternity, The Law Offices of Curtis Bennett Ross, L.L.C. can review your situation and explain what options may still be open to you.

Our Cook County, IL family law attorney has practiced since 1984, bringing more than 40 years of experience to parentage cases. Attorney Curtis Ross is also a certified public accountant, court-appointed financial expert and receiver, trained mediator, and court-approved Guardian ad Litem in Cook County, giving him insight into cases involving both children and finances.

Call The Law Offices of Curtis Bennett Ross, L.L.C. at 312-984-1514 to schedule your free limited consultation today.