Can Paternity Be Established After the Child Turns 18?

In Washington, an adult child can often still establish parentage, because the person whose parentage is being decided is one of the people the law allows to bring the case. The reasons for doing so, from inheritance to benefits to simple identity, tend to be significant.

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The Short Answer

Many people assume that once a child reaches adulthood, the window to establish paternity has closed for good. In Washington, that assumption is often wrong. The state's Uniform Parentage Act, chapter 26.26A RCW, gives standing to bring a parentage case to several people, and the child is one of them. That means an adult who was never legally connected to a parent may still have a path to establishing that relationship, though the details depend on the specific facts and on which parts of the statute apply.

Who Is Allowed to Bring a Parentage Case

Standing, in plain terms, means who is legally permitted to start a case. Under RCW 26.26A.405, a proceeding to adjudicate parentage may be maintained by a defined list of people. That list includes the child, the woman who gave birth to the child, an individual who is already a parent under the chapter, and, importantly, an individual whose parentage of the child is to be adjudicated. The division of child support and certain agencies also appear on the list.

Because the statute names "the child" without capping that person's age, an adult son or daughter generally falls within the group of people who can maintain a proceeding. The same section also allows a representative authorized by law to act for someone who would otherwise be entitled to bring a case but is deceased, incapacitated, or a minor, found in RCW 26.26A.405(7). This matters when the person whose parentage is at issue has died, because it opens a route for an authorized representative to pursue the question on that person's behalf.

Are There Time Limits?

Washington's parentage law does contain timing rules, but they are not a single blanket deadline that shuts every door on a person's eighteenth birthday. The standing section, RCW 26.26A.405, does not itself impose a hard cutoff on an adult child. Instead, the timing rules that apply to a given case depend on the circumstances, such as whether the child already has a presumed, acknowledged, or adjudicated parent, and those situations are governed by other sections within the same chapter. Because the answer turns on which specific provisions apply to your facts, this is an area where a careful review by a family law attorney is genuinely valuable. The takeaway is that turning eighteen does not automatically end the possibility, but the surrounding rules can shape and sometimes limit it.

Common Reasons Adults Pursue Parentage

People do not usually seek to establish parentage as an adult for sentimental reasons alone, though identity and family history certainly matter to many. The most common practical drivers involve rights and benefits that flow from the legal relationship.

Inheritance is one of the most frequent. When a parent dies without a will, Washington's intestate succession rules determine who inherits, and a legally recognized child typically stands to inherit while an unrecognized biological child may not. Establishing parentage can therefore be the difference between having a claim to an estate and having none. Benefits are another major reason. Certain government and survivor benefits, including some Social Security survivor benefits, can depend on a legally established parent-child relationship. Adults sometimes discover, often after a parent's death or a benefits denial, that the missing legal link is exactly what stands between them and a benefit they would otherwise receive.

There are also more personal but still concrete reasons, such as obtaining an accurate medical family history or correcting a birth record. Whatever the motivation, the legal mechanism is the same: a proceeding to adjudicate parentage brought by someone with standing to do so.

How the Process Generally Works

A parentage case is a civil proceeding. Under RCW 26.26A.400, a proceeding may be commenced to adjudicate the parentage of a child, and it is governed by the ordinary rules of civil procedure except where the chapter provides otherwise. Within that proceeding, the court has authority under RCW 26.26A.310 to order genetic testing when a party's sworn statement supports it, which is often central when the alleged parent is available to be tested. When the alleged parent has died, the case becomes more complex, and other tools within the chapter, such as testing of close relatives in appropriate circumstances, may come into play.

A Snohomish County Perspective

For families in Snohomish County, these situations arise more often than people expect, frequently surfacing during the difficult period after a parent's death, when an estate is being settled or benefits are being sought. Acting sooner rather than later tends to make everything easier, because evidence is fresher and the people who can be tested are more likely to be available. If you are an adult who never had a legal parent established, or you are helping a family member navigate one of these questions, it is worth understanding your options before a deadline in a related matter, such as probate, forces your hand.

If you are wondering whether you can still establish parentage as an adult, or you need help protecting an inheritance or benefit that depends on it, the Law Office of Chad Foster can help you understand the path that fits your situation.