Adult Adoption in Washington State

Adult adoption in Washington State is one of the simplest legal proceedings available in family law — and also one of the least understood. Most adoption resources focus on children, but RCW 26.33 explicitly permits the adoption of adults. The process requires no home study, no termination of biological parental rights, and no involvement from DCYF. It exists to formalize relationships that already exist in practice, and it carries real legal consequences for inheritance, next-of-kin status, and medical decision-making.

If you are considering adopting an adult — or being adopted as an adult — here is how the process works in Washington.

Who Uses Adult Adoption

The most common scenarios fall into a few categories:

Stepparent formalization. A stepparent who has raised a child but never completed the legal adoption during childhood. Once the child reaches 18, the adult child and stepparent can complete the adoption without needing consent from the other biological parent. This is the simplest path because it removes the contested TPR process entirely.

Inheritance and estate planning. Washington inheritance law gives adopted children the same rights as biological children. An adult adoption creates a legal parent-child relationship that entitles the adoptee to inherit under intestacy law and to be named as a beneficiary without the complications that can arise with unrelated individuals in estate disputes.

Long-standing caregiving relationships. Foster children who aged out of the system, godchildren, or family friends who were raised by someone other than their biological parents. Adult adoption provides legal recognition of the relationship that has existed for years or decades.

Emotional closure. For some families, the adoption decree is not about legal rights at all — it is about formally acknowledging a bond. Washington courts recognize this as a valid purpose.

Requirements Under RCW 26.33

The requirements for adult adoption are minimal compared to child adoption:

Consent. Only two people need to consent: the adoptive parent and the adult adoptee. No biological parent's consent or TPR is required. The biological parents do not need to be notified, although they will lose their legal parental rights once the decree is entered.

No home study. The pre-placement report requirement that applies to all child adoptions is waived for adult adoptions. No social worker will visit your home or assess your living situation.

No background checks. The WSP, FBI, and CAMIS clearances required for child adoption do not apply.

Petition filing. The adoptive parent files a Petition for Adoption in the Superior Court of the county where the petitioner resides or where the adoptee is domiciled. The filing fee is approximately $260 in most Washington counties.

The Court Process

The process is straightforward:

1. File the Petition for Adoption with the Superior Court, along with the filing fee and a proposed Decree of Adoption.
2. Both the adoptive parent and the adult adoptee appear before the judge (or submit declarations, depending on county practice).
3. The judge confirms that both parties consent and that the adoption is not being pursued for fraudulent purposes.
4. The court enters the Decree of Adoption.
5. The Department of Health issues an amended birth certificate listing the adoptive parent, if requested.

In King County, the Superior Court's Adoption Services department handles adult adoptions through the same filing system as child adoptions, with standardized packets available. Smaller counties process adult adoptions on their general motion docket.

The entire process — from filing to decree — can be completed in as little as a few weeks, depending on court scheduling. There is no six-month waiting period for adult adoptions.

Legal Effects

Once the decree is entered, the legal consequences are identical to those of a child adoption under RCW 26.33.260:

• The biological parents lose all legal rights and obligations toward the adoptee
• The adoptee becomes the legal heir of the adoptive parents for all purposes
• The adoptee gains next-of-kin status for medical decisions, hospital visitation, and insurance purposes
• The adoptee can take the adoptive parent's surname through the decree without a separate name change proceeding

One important consideration: adult adoption is irrevocable. Unlike some states that allow adult adoptions to be dissolved, Washington treats the decree as permanent. Both parties should understand this before proceeding.

Common Misconceptions About Adult Adoption

"My biological parents have to agree." They do not. Adult adoption in Washington requires only the consent of the adoptive parent and the adult adoptee. Biological parents are not parties to the proceeding and cannot block it. Their legal relationship to the adoptee is severed by the decree whether they consent or not.

"I can adopt my spouse." Washington law does not permit the adoption of a spouse. The relationship between spouses is governed by marriage law, not adoption law.

"Adult adoption gives me citizenship or immigration benefits." Adoption of an adult does not confer the same immigration benefits as adoption of a child. If immigration status is a factor, consult an immigration attorney before proceeding — the intersection of adoption law and immigration law is complex and the outcomes are case-specific.

"I am too old to be adopted." There is no upper age limit for adult adoption in Washington. The statute applies to any person aged 18 or older.

When an Attorney Is Helpful

While adult adoption is simple enough that some families file pro se (without an attorney), an attorney is useful in situations involving:

• Complex inheritance implications, especially blended families where biological children and adopted adults will share an estate
• Cases where the adoptee is a non-citizen, as adoption may affect immigration status
• Situations where biological parents may attempt to contest the adoption (they generally have no standing, but the filing may prompt a response)
• Same-sex couples where one partner wants to formally adopt the other partner's adult child from a prior relationship

For a broader understanding of how adoption works in Washington — including the legal framework under RCW 26.33, court filing procedures by county, and how adult adoption compares to other adoption types — the Washington Adoption Process Guide covers the full landscape.

Get the Washington Adoption Process Guide

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