How to Establish Paternity in Illinois
Reviewed by DocDraft Legal Team · Illinois · Last updated 2026-09-12
In Illinois, establishing paternity means legally recognizing a child's parent so the child receives support, parenting time, health coverage, inheritance, and benefits. Illinois uses the term parentage, and its rules are in the Illinois Parentage Act of 2015 (750 ILCS 46). Parents who agree can sign a Voluntary Acknowledgment of Parentage, form HFS 3416B, which has the effect of a court order and can be rescinded within 60 days. Two Illinois rules are load-bearing. First, timing: where a child has no presumed, acknowledged, or adjudicated parent, a proceeding to adjudicate parentage may be commenced at any time (750 ILCS 46/607); where a child has a presumed parent, an action by someone other than the child to challenge that presumption must be commenced within 2 years after the petitioner knew or should have known the relevant facts (750 ILCS 46/608). Second, the genetic-testing threshold: a person is presumed to be a parent when testing shows a combined parentage index of at least 1,000 to 1 and at least a 99.9 percent probability of parentage (750 ILCS 46/404). A person married to the birth parent is a presumed parent, and that presumption is rebutted by clear and convincing evidence (750 ILCS 46/204). Attorney review of your situation is available through DocDraft.
Find out where you stand in Illinois
Where are you in establishing paternity?
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How long do I have to establish parentage in Illinois?
Under the Illinois Parentage Act of 2015, where a child has no presumed, acknowledged, or adjudicated parent, a proceeding may be commenced at any time (750 ILCS 46/607). Where a child has a presumed parent, an action by someone other than the child to challenge it must be commenced within 2 years of knowing the relevant facts (750 ILCS 46/608).
What is the marital presumption of parentage in Illinois?
Under 750 ILCS 46/204, a person is presumed to be a parent if married or in a civil union with the birth parent and the child is born during that relationship, or within 300 days after it ends. That presumption is rebutted by clear and convincing evidence in a proceeding under the Illinois Parentage Act of 2015.
What genetic test result establishes parentage in Illinois?
Under 750 ILCS 46/404, genetic testing presumes a person to be a parent when the results show a combined parentage index of at least 1,000 to 1 and at least a 99.9 percent probability of parentage. A person so identified may rebut only with further genetic testing that excludes them or identifies another parent.
Who handles parentage cases in Illinois?
The Illinois Department of Healthcare and Family Services, through its Division of Child Support Services, helps parents establish parentage and support and provides the Voluntary Acknowledgment of Parentage, form HFS 3416B. Contested cases are decided by the circuit court, which can order genetic testing.
Illinois parentage law at a glance
Illinois speaks of parentage rather than paternity, and its rules sit in the Illinois Parentage Act of 2015 (750 ILCS 46). Parents who agree can establish parentage by signing a Voluntary Acknowledgment of Parentage, form HFS 3416B, filed with the Department of Healthcare and Family Services, with a 60-day right to rescind. The timing rules are the payload here. Where a child has no presumed, acknowledged, or adjudicated parent, a proceeding may be commenced at any time (750 ILCS 46/607). Where a child has a presumed parent, an action by someone other than the child must be commenced within 2 years after the petitioner knew or should have known the facts (750 ILCS 46/608). Genetic testing presumes parentage at a combined parentage index of 1,000 to 1 and a 99.9 percent probability (750 ILCS 46/404), and the marital presumption is rebutted by clear and convincing evidence (750 ILCS 46/204).
Establishing Illinois parentage where a presumed parent exists
Suppose a child is born in Illinois while the birth parent is married, but another person believes they are the biological parent. Because the spouse is a presumed parent under 750 ILCS 46/204, anyone other than the child must challenge that presumption within 2 years after the challenger knew or should have known the facts (750 ILCS 46/608). They ask the circuit court for genetic testing, and a result showing a combined parentage index of at least 1,000 to 1 and at least a 99.9 percent probability of parentage presumes a parent (750 ILCS 46/404). The marital presumption itself yields only to clear and convincing evidence. With no presumed parent, the proceeding could be brought at any time (750 ILCS 46/607). Had the parents agreed, they could have signed the Voluntary Acknowledgment of Parentage, form HFS 3416B, with a 60-day right to rescind. Attorney review is available through DocDraft.
Relevant Laws
750 ILCS 46/607 (no limitation where no presumed parent)
Provides that a proceeding to adjudicate the parentage of a child having no presumed, acknowledged, or adjudicated parent may be commenced at any time, even after the child becomes an adult if the child initiates the proceeding.
750 ILCS 46/608 (limitation where a child has a presumed parent)
Requires that an action to challenge a presumption of parentage under Section 204 be commenced by an individual other than the child not later than 2 years after the petitioner knew or should have known the relevant facts, with the 2-year limit not applying to an action by the child.
750 ILCS 46/404 (genetic-testing threshold)
Provides that where genetic testing indicates the alleged genetic parent is not excluded and the combined parentage index is at least 1,000 to 1 with at least a 99.9 percent probability of parentage, the alleged genetic parent is presumed to be the parent, rebuttable only by further genetic testing.
750 ILCS 46/204 (presumption of parentage)
Provides that a person is presumed to be a parent if married to or in a civil union with the birth parent and the child is born during that relationship, or within 300 days after it is terminated, among other grounds.
Illinois Department of Healthcare and Family Services, Child Support Services
The Department of Healthcare and Family Services, through its Division of Child Support Services, provides the Voluntary Acknowledgment of Parentage (form HFS 3416B), can order genetic testing administratively, and can establish and enforce support.
Regional Variances
Illinois parentage rules at a glance
Voluntary path and form
Parents who agree establish parentage by signing the Voluntary Acknowledgment of Parentage, form HFS 3416B, filed with the Department of Healthcare and Family Services, which has the effect of a court order.
Rescission window
A signer may rescind before the earlier of 60 days after the acknowledgment's effective date, or a proceeding relating to the child. After that it can be challenged only for fraud, duress, or material mistake of fact.
Marital presumption and deadline
A spouse or civil-union partner of the birth parent is a presumed parent (750 ILCS 46/204); a challenge by someone other than the child must be commenced within 2 years of knowing the relevant facts (750 ILCS 46/608).
Deadline where no presumed parent exists
Where a child has no presumed, acknowledged, or adjudicated parent, a proceeding may be commenced at any time, even into adulthood if the child brings it (750 ILCS 46/607).
Genetic-testing threshold
Genetic testing presumes parentage at a combined parentage index of at least 1,000 to 1 with at least a 99.9 percent probability of parentage (750 ILCS 46/404).
Who administers it
The Department of Healthcare and Family Services, Division of Child Support Services, administers acknowledgment and support, while contested parentage is decided by the circuit court, which can order genetic testing.
Suggested Compliance Checklist
Confirm whether a presumed parent exists
Before signing or filing anything days after startingDetermine whether the birth parent was married or in a civil union when the child was born or within 300 days before, which makes the spouse or partner a presumed parent (750 ILCS 46/204). A challenge by someone other than the child must be commenced within 2 years of knowing the relevant facts (750 ILCS 46/608).
Get genetic testing if parentage is uncertain
Before signing an acknowledgment days after startingBecause the acknowledgment carries the force of a judgment, obtain genetic testing first if there is doubt. Under 750 ILCS 46/404, a combined parentage index of at least 1,000 to 1 and at least a 99.9 percent probability of parentage presume a person to be a parent.
Sign and file the Voluntary Acknowledgment of Parentage
At the hospital or a local office days after startingParents who agree sign form HFS 3416B and file it with the Department of Healthcare and Family Services, where it has the effect of a court order of parentage. Keep a copy. Attorney review of your parentage matter is available through DocDraft.
Track the 60-day rescission window
Within 60 days of the effective date days after startingIf you need to cancel a signed acknowledgment, rescind before the earlier of 60 days after its effective date, or a proceeding relating to the child. After 60 days it can be undone only for fraud, duress, or material mistake of fact.
File a parentage action in court if parents disagree
Within the applicable limitation period days after startingIf parents do not agree, ask the Division of Child Support Services to open a case or file a proceeding to adjudicate parentage in the circuit court under 750 ILCS 46. Where no presumed parent exists the action may be filed at any time (750 ILCS 46/607).
Keep records of the acknowledgment, testing, and orders
Ongoing days after startingSave copies of the signed acknowledgment, any genetic-test results, and court papers, and calendar the 60-day rescission window and any 2-year challenge deadline (750 ILCS 46/608) so you do not miss a right-forfeiting date.
| Task | Description | Document | Days after starting |
|---|---|---|---|
| Confirm whether a presumed parent exists | Determine whether the birth parent was married or in a civil union when the child was born or within 300 days before, which makes the spouse or partner a presumed parent (750 ILCS 46/204). A challenge by someone other than the child must be commenced within 2 years of knowing the relevant facts (750 ILCS 46/608). | - | Before signing or filing anything |
| Get genetic testing if parentage is uncertain | Because the acknowledgment carries the force of a judgment, obtain genetic testing first if there is doubt. Under 750 ILCS 46/404, a combined parentage index of at least 1,000 to 1 and at least a 99.9 percent probability of parentage presume a person to be a parent. | - | Before signing an acknowledgment |
| Sign and file the Voluntary Acknowledgment of Parentage | Parents who agree sign form HFS 3416B and file it with the Department of Healthcare and Family Services, where it has the effect of a court order of parentage. Keep a copy. Attorney review of your parentage matter is available through DocDraft. | - | At the hospital or a local office |
| Track the 60-day rescission window | If you need to cancel a signed acknowledgment, rescind before the earlier of 60 days after its effective date, or a proceeding relating to the child. After 60 days it can be undone only for fraud, duress, or material mistake of fact. | - | Within 60 days of the effective date |
| File a parentage action in court if parents disagree | If parents do not agree, ask the Division of Child Support Services to open a case or file a proceeding to adjudicate parentage in the circuit court under 750 ILCS 46. Where no presumed parent exists the action may be filed at any time (750 ILCS 46/607). | - | Within the applicable limitation period |
| Keep records of the acknowledgment, testing, and orders | Save copies of the signed acknowledgment, any genetic-test results, and court papers, and calendar the 60-day rescission window and any 2-year challenge deadline (750 ILCS 46/608) so you do not miss a right-forfeiting date. | - | Ongoing |
Frequently Asked Questions
Establishing parentage in Illinois means legally recognizing a child's parent so the child receives support, parenting time, health coverage, inheritance, and benefits. Under the Illinois Parentage Act of 2015 it is done by signing a Voluntary Acknowledgment of Parentage or through a court proceeding to adjudicate parentage (750 ILCS 46).
Parents who agree sign a Voluntary Acknowledgment of Parentage, form HFS 3416B, filed with the Department of Healthcare and Family Services, which has the effect of a court order. If parents disagree, the circuit court adjudicates parentage under 750 ILCS 46, usually after ordering genetic testing.
It is a form, HFS 3416B, that parents sign to establish a legal parent-child relationship without going to court. Once completed and filed with the Department of Healthcare and Family Services it has the same effect as a court order of parentage and can support a child support order.
An action by someone other than the child to challenge a presumed parent must be commenced within 2 years after the petitioner knew or should have known the relevant facts (750 ILCS 46/608). Missing that window can lock in the presumed parent, though the 2-year limit does not apply to an action brought by the child.
A person married to or in a civil union with the birth parent is a presumed parent under 750 ILCS 46/204. That presumption is rebutted by clear and convincing evidence, and a challenge by someone other than the child must be brought within 2 years of knowing the relevant facts (750 ILCS 46/608).
Yes, within a limited window. A signer may rescind a Voluntary Acknowledgment of Parentage by filing with the Department of Healthcare and Family Services before the earlier of 60 days after its effective date, or a proceeding relating to the child. After 60 days it can be challenged only for fraud, duress, or material mistake of fact.
Not by itself. Under 750 ILCS 46/404, testing showing a combined parentage index of at least 1,000 to 1 and at least a 99.9 percent probability of parentage presumes a parent, but parentage is finalized by a signed acknowledgment or a court judgment, not the lab report alone.
Where a child has no presumed, acknowledged, or adjudicated parent, a proceeding to adjudicate parentage may be commenced at any time, even into adulthood if the child brings it (750 ILCS 46/607). The main hard deadline applies to challenging an existing presumed parent (750 ILCS 46/608).
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