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.