Oregon Paternity: Establishing Parentage Under ORS 109

In Oregon, paternity — now called parentage in the statutes — is established in one of four common ways: by being married to the birth parent when the child is born, by both parents signing and filing a voluntary acknowledgment of parentage, by an administrative order through the Oregon Child Support Program, or by a circuit court judgment. Until parentage is established in one of those ways, or another way listed in ORS 109.065 such as adoption or an acknowledgment signed in another state, an unmarried father is not a legal parent.

Senate Bill 163 (Oregon Laws 2025, chapter 592) rewrote much of ORS chapter 109 starting January 1, 2026, using terms such as alleged genetic parent. Articles citing ORS 109.250 to 109.262 or ORS 416.400 to 416.470 cite repealed or renumbered sections.

This article is general information, not legal advice, and creates no attorney-client relationship. The governing law is ORS chapter 109, with the administrative process in ORS 25.501 to 25.556. For the custody and parenting-time questions that usually follow, see our guides to how Oregon courts decide custody and modifying an Oregon parenting plan, and our family law practice.

Table of Contents

• ➤ The Four Ways Parentage Is Established
• ➤ The Marriage Presumption (ORS 109.067)
• ➤ The Voluntary Acknowledgment of Parentage
• ➤ Rescinding or Challenging an Acknowledgment
• ➤ Administrative Parentage Through the Child Support Program
• ➤ A Court Parentage Case (ORS 109.124 to 109.171)
• ➤ Genetic Testing: The 99 Percent Rule
• ➤ What Establishing Parentage Does Not Do
• ➤ Unmarried Fathers: Protecting Your Position
• ➤ Changes Taking Effect January 1, 2027
• ➤ Frequently Asked Questions
• ➤ Talk to a BFQ Law Oregon Attorney

The Four Ways Parentage Is Established

ORS 109.065 lists every way parentage can be established. Leaving aside birth, adoption and assisted reproduction, four routes matter in a typical paternity question:

Route	Who uses it	Governing law
Marriage presumption	A spouse of the birth parent at the time of birth, or within 300 days after the marriage ends	ORS 109.067
Voluntary acknowledgment	Unmarried parents who agree on parentage, usually at the hospital	ORS 109.070; ORS 432.098
Administrative order	Cases opened with the Oregon Child Support Program	ORS 25.501 to 25.556
Court judgment	Disputed cases, or cases joined with custody and support	ORS 109.124 to 109.171

The routes are not ranked: an effective acknowledgment equals a court adjudication, and an administrative order establishes legal parentage for all purposes (ORS 25.550(3)). What differs is how easily each can be undone.

The Marriage Presumption (ORS 109.067)

Under ORS 109.067(1), a person is rebuttably presumed to be the parent of a child if they were married to the parent who gave birth at the time of the birth (without a judgment of separation, and even if the marriage is void), or if the child is born within 300 days after the marriage ended by death, annulment or dissolution, or after a judgment of separation.

Three limits protect the presumption:

• Who can challenge it. A presumption based on a current marriage may be challenged by the birth parent or the presumed parent. No one else may challenge it while those two are cohabiting, unless both consent.
• The age-four cutoff. The presumption cannot be rebutted after the child turns four unless the court finds the presumed parent is not a genetic parent, never lived with the child and never held the child out as their own; the child has more than one presumed parent; or the presumption arose from fraud, duress or a material mistake of fact. The four-year limit also does not apply to certain challenges involving conception by rape (ORS 109.148) or assisted reproduction (ORS 109.213).
• The age-18 cutoff. Any challenge must be started before the child turns 18, unless the child brings it.

Where competing claims reach the court, ORS 109.151 directs a best-interests decision that weighs the child’s age, how long each person has acted as a parent and the harm of not recognizing each relationship. A genetic test showing someone else is the biological father is evidence in that analysis, not an automatic answer.

The Voluntary Acknowledgment of Parentage

For unmarried parents who agree, the simplest route is the voluntary acknowledgment of parentage form (still widely called the “voluntary acknowledgment of paternity”). Under ORS 109.070(1), the parent who gave birth and the alleged genetic parent establish parentage by filing the form with the State Registrar of the Center for Health Statistics. The form rules are in ORS 432.098, which was numbered ORS 432.287 until 2013.

• The acknowledgment takes effect when the form is filed with the state registrar (ORS 432.098(1)(d)).
• Signatures must be notarized, or witnessed by staff at the birth facility if signed within five days of the birth (ORS 109.070(3)(g)).
• If no second parent is on the birth record, filing puts the acknowledging parent’s name on it (ORS 432.098(1)(b)).
• Unless rescinded or successfully challenged, the acknowledgment is equivalent to an adjudication of parentage and confers all the rights and duties of a parent (ORS 109.070(4)).
• An acknowledgment is void if another person is already the child’s presumed, acknowledged, adjudicated or intended parent when it is signed (ORS 109.070(8)(b) and (c)). A married birth parent’s spouse is a presumed parent, so the form cannot simply bypass the spouse.

Rescinding or Challenging an Acknowledgment

Window	What is allowed	Source
Up to 60 days after the acknowledgment takes effect, or the date of the first court hearing about the child (including a support case) in which the rescinding party is a party, whichever is earlier	Rescission for any reason, by a signed, notarized written rescission filed with the state registrar	ORS 109.070(5)
Within one year after the acknowledgment takes effect	A party may apply to the Child Support Program for an order for genetic testing, if testing has not already been done; if the results exclude the acknowledged parent, the program may ask the court to set the acknowledgment aside	ORS 109.070(7); ORS 25.554(2), (5)
Any time after the 60-day period	A circuit court challenge, only on the basis of fraud, duress or a material mistake of fact	ORS 109.070(6)

In a court challenge the challenger bears the burden of proof, and support continues during the case absent good cause. Even if fraud, duress or mistake is shown by a preponderance of the evidence, the court will not set the acknowledgment aside if doing so would be substantially inequitable, considering the interests of the parties and the child.

If parentage was set by a judgment or administrative order entered without genetic testing and without a contest, ORS 109.072 offers a separate petition to vacate. It must be filed within one year of the judgment for mistake, inadvertence, surprise or excusable neglect, or within one year of discovering fraud or misconduct by the other party.

Administrative Parentage Through the Child Support Program

Many Oregon parentage cases never start in court. The Oregon Child Support Program, run by the Department of Justice, can establish parentage as part of setting support under ORS 25.501 to 25.556. The Oregon Judicial Department’s forms page for unmarried parents says a parent can ask the program to do this by submitting an Application for Child Support Services and a Declaration in Support of Establishing Parentage, and lists a $1 fee for the service.

• If both parents sign statements that parentage has not been established and that the alleged genetic parent is the parent, the administrator may enter an order establishing parentage (ORS 25.550(1)).
• Otherwise the administrator issues a notice and proposed order. A notice that involves establishing parentage must be personally served (ORS 25.511(1)(a)).
• The person served has 30 days from service to send a written response denying parentage and requesting a hearing (ORS 25.511(2)(g)). If no timely denial arrives, the administrator may enter an order declaring that person the legal parent without further notice (ORS 25.550(2)).
• A timely denial generally leads to genetic testing. If the results show a combined relationship index of 99 or greater, are served on the parties, and no one objects in writing within 30 days, the administrator may enter an order establishing parentage (ORS 25.550(5) and (7)). A timely written objection, a result below 99, or a written request made at least 120 days after a denial sends the case to circuit court (ORS 25.550(6)).

One costly mistake is ignoring the paperwork: an unanswered notice can become a parentage order and a support order with collection tools attached.

A Court Parentage Case (ORS 109.124 to 109.171)

A filiation case — now called a proceeding to adjudicate parentage — is filed in circuit court. Under ORS 109.125, it can be started by the parent who gave birth, the alleged genetic parent, the child, a presumed or acknowledged parent, a guardian with custody, or the child support administrator. It must be started before the child turns 18 unless the child brings it.

• It is tried without a jury, generally in the county where the child lives (ORS 109.135).
• The court can order past and future support, and the reasonable expenses of prenatal care, the birth and postnatal care (ORS 109.155(5)).
• On a party’s motion, the court will enter a temporary child support order pending the decision; for that purpose it may presume parentage of, for example, a presumed parent, someone identified by genetic testing, or someone who declined testing (ORS 109.154).
• The petitioner must serve notice of the filing on the Center for Health Statistics (ORS 109.167), which matters for unmarried fathers (see below).

A parentage case can be consolidated with a custody or support case (ORS 109.127).

Genetic Testing: The 99 Percent Rule

Since January 1, 2026, genetic testing is governed by ORS 109.181 to 109.203. Most of the former ORS 109.250 to 109.262 was repealed, and the temporary-support provision moved to ORS 109.154. The core rules:

Rule	Detail	Source
When testing must be ordered	On a party’s sworn statement alleging a reasonable possibility that someone is, or is not, the genetic parent	ORS 109.184(1)(b)
When it may be refused	Where the child has a presumed parent or an acknowledgment is being challenged, after the court weighs the ORS 109.151 best-interests factors	ORS 109.184(5)
Presumption of genetic parentage	At least a 99 percent probability of parentage and a combined relationship index of at least 100 to 1	ORS 109.191(1)
Objecting to the report	An objection to admitting a court-ordered report, no later than 14 days after receiving it, citing specific grounds for exclusion	ORS 109.189(2)
Refusing to test	The court may resolve parentage against the person who refuses, or find them in contempt	ORS 109.184(7)

A test result that meets the 99 percent threshold can be challenged only by other qualifying genetic testing that excludes the person or identifies another possible genetic parent (ORS 109.191(2)). A private test kit bought online may not satisfy the statute’s laboratory accreditation and chain-of-custody requirements in ORS 109.186 and 109.188.

What Establishing Parentage Does Not Do

Establishing parentage makes you a legal parent with the same status as any other parent (ORS 109.060 and 109.094). It does not, on its own, give you a custody order or a parenting-time schedule.

Under ORS 109.161, when parentage of a child born to unmarried parents is established by acknowledgment, administrative order or court petition, the parent who had physical custody at the time of filing has sole legal custody until a court specifically orders otherwise. In practice that is usually the birth parent. A father with a signed acknowledgment but no court order has no enforceable parenting-time schedule.

The fix is a custody and parenting-time case under ORS 109.103. Once parentage is established, either parent may file, and the parents have the same rights and responsibilities regarding custody, support and parenting time that married or divorced parents would have. The first time a court decides custody, neither parent has to prove a change of circumstances, and the court applies the best-interests standards of ORS 107.137 (ORS 109.161(1)). Our Oregon child custody guide covers how those factors are weighed, and our UCCJEA guide explains which state’s courts can hear the case when a parent has moved.

Unmarried Fathers: Protecting Your Position

Timing matters most when adoption is possible. Under ORS 109.096, an alleged genetic parent is entitled to notice of an adoption only in defined situations, such as having lived with the child in the prior 60 days, having repeatedly contributed or tried to contribute support, or having a notice of a pending parentage case on file with the Center for Health Statistics. If that notice is not on file before the child is placed for adoption, the statute says the alleged genetic parent is barred from contesting the adoption.

Steps unmarried fathers commonly consider:

• Where both parents agree and neither doubts biology, signing and filing the acknowledgment.
• Where either parent has doubts, getting court- or program-ordered genetic testing before signing anything.
• Where adoption is possible, filing a parentage case promptly so the ORS 109.167 notice is on file before any placement.
• Once parentage is established, filing under ORS 109.103 for custody and parenting time rather than relying on an informal arrangement.
• Responding to any Child Support Program notice within the 30 days it states.

Changes Taking Effect January 1, 2027

A second set of SB 163 amendments takes effect January 1, 2027 (Oregon Laws 2025, chapter 592, section 153):

• An acknowledgment of parentage may be signed and filed before the child is born; it takes effect at the birth or the filing, whichever is later (ORS 432.098 as amended).
• A presumed parent or alleged genetic parent may sign a written denial of parentage. It works only alongside another person’s filed acknowledgment, which may be filed before, at the same time as or after the denial. It carries the same 60-day rescission window, and rescinding either form invalidates the other.
• A new presumption covers a person who intends to marry the birth parent and agrees to be, and is, named on the birth record.

Frequently Asked Questions

Is the father automatically on the birth certificate if we are not married? No. Without a marriage presumption, a second parent is added through a filed acknowledgment of parentage, an administrative order or a court judgment, after which the birth record is updated to name that parent (ORS 432.098(1)(b); ORS 109.094; ORS 25.550(3)).

How long do I have to cancel a voluntary acknowledgment? Sixty days after it takes effect, or the date of the first court hearing about the child in which you are a party, whichever is earlier (ORS 109.070(5)). After that, the main option is a circuit court challenge for fraud, duress or material mistake of fact (ORS 109.070(6)). Separately, for one year after the acknowledgment takes effect, a party can ask the Child Support Program for genetic testing if none has been done; a result excluding the acknowledged parent lets the program ask the court to set the acknowledgment aside (ORS 109.070(7); ORS 25.554).

Talk to a BFQ Law Oregon Attorney

Most Oregon paternity questions turn on three things: which route established parentage, or still can, whether any deadline to rescind or challenge has passed, and whether a custody and parenting-time order exists yet. Answer those with the actual documents — the acknowledgment, the Child Support Program notice, any judgment — and the available options become much easier to see.

Read about our attorneys and legal team, our family law practice, or our guide to Oregon divorce laws, custody and support. Reach us through our contact page. Nothing here promises an outcome, and every parentage case depends on its own facts and dates.