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How to Adopt an Adult in Washington

Reviewed by DocDraft Legal Team · Washington · Last updated October 7, 2026

Adult adoption in Washington is a superior court case that permanently makes one adult the legal parent of another adult, carrying the inheritance and next of kin consequences that follow. Washington then writes the eligibility rule about as broadly as it can be written. RCW 26.33.140(1) says any person may be adopted, regardless of his or her age or residence. There is no list of approved categories, no disability or former stepchild requirement, no minimum number of years between you, and no rule that the person being adopted be younger. That person does not even have to live in Washington. The statute asks only that you be legally competent and at least eighteen (RCW 26.33.140(2)). Washington is strict in a different place. If you are married, your spouse must join in the petition, and the adoption chapter states no exception for separation, absence or good cause (RCW 26.33.150(4)). That duty reaches a state registered domestic partner too (RCW 26.33.902). The consents are short. The person being adopted signs one, because the threshold is age fourteen (RCW 26.33.160(1)(a)). Birth parents sign nothing, since that clause reaches only an adoptee under eighteen. The consent list never mentions the spouse of the person being adopted. No preplacement or post-placement report is required once the adoptee is eighteen or older (RCW 26.33.220), which also removes the fingerprint check sitting inside that report. You file in the county where you live or where the adoptee is domiciled and pay $290. Washington publishes no statewide adoption forms. Attorney review of your paperwork is available through DocDraft.

Find out where you stand in Washington

Who are you hoping to adopt?

DocDraft provides document preparation, not legal advice.

Who can be adopted as an adult in Washington?

Any person may be adopted in Washington, regardless of his or her age or residence (RCW 26.33.140(1)). There is no list of qualifying categories, and no requirement that the person be younger than you or live in the state. The adopting person must be legally competent and at least eighteen.

Does my spouse have to sign off on a Washington adult adoption?

Your spouse does more than sign. If the petitioner is married, the petitioner's spouse shall join in the petition (RCW 26.33.150(4)), becoming a co-petitioner. Washington's adoption chapter states no exception for separation, absence or good cause. The same duty reaches a state registered domestic partner (RCW 26.33.902).

What does it cost to file an adult adoption in Washington?

Washington sets $290 in statewide charges. The base is $200 for the first document in any civil action, and adoption is named in that provision (RCW 36.18.020(2)(a)). Two mandatory surcharges follow, $40 under subsection (5)(c) and $50 under subsection (6). County copy and service costs are separate.

Which court handles an adult adoption in Washington?

The superior court. Washington's adoption chapter defines court to mean the superior court (RCW 26.33.020(7)). File the petition in the superior court of the county where you are a resident, or the county where the person being adopted is domiciled (RCW 26.33.030(1)). No durational residency applies.

Washington adult adoption at a glance

An adult adoption in Washington is a court order making one adult the permanent legal parent of another adult, so the adoptee becomes the child, legal heir and lawful issue of the adoptive parent (RCW 26.33.260(1)). Washington's eligibility rule is the widest part of the process. Any person may be adopted, regardless of his or her age or residence (RCW 26.33.140(1)), so no category list applies, no minimum age gap exists, and the adoptee need be neither younger than you nor a Washington resident. The tight spot is joinder. A married petitioner's spouse must join the petition, with no stated exception (RCW 26.33.150(4)). No preplacement or post-placement report is required once the adoptee is eighteen or older (RCW 26.33.220). You file in superior court, pay $290, and work without statewide forms.

Adopting an adult stepson who is older than you

Consider a Kitsap County welder of 49 who married a woman of 61 and now wants her 54 year old son, five years his senior, recorded as his legal child. Washington does not blink at the inversion, because any person may be adopted, regardless of his or her age or residence (RCW 26.33.140(1)), and the fact that the son lives outside Washington does not matter either. Since the welder is married, his wife must join the petition even though she is the adoptee's own mother, as Washington states no exception (RCW 26.33.150(4)). Her legal tie survives regardless, because the decree divests only a parent who is not married to the adoptive parent (RCW 26.33.260(1)). The son signs one consent. They file in Kitsap County superior court and pay $290. Attorney review is available through DocDraft.

Relevant Laws

RCW 26.33.140 (who may adopt or be adopted)

Provides that any person may be adopted, regardless of his or her age or residence, and that any person who is legally competent and who is eighteen years of age or older may be an adoptive parent. Washington attaches no category list to adult adoption.

RCW 26.33.150 (petition for adoption and spousal joinder)

Sets the four items a petition for adoption must contain, requires the petition be signed under penalty of perjury, and provides that if the petitioner is married, the petitioner's spouse shall join in the petition. No exception to joinder is stated.

RCW 26.33.160 (whose consent to adoption is required)

Requires consent of the adoptee if fourteen years of age or older, and of the parents and any alleged father only of an adoptee under eighteen years of age. The list does not include the spouse of the person being adopted.

RCW 26.33.220 (when the preplacement and post-placement reports are not required)

Provides that the reports required by RCW 26.33.190 and RCW 26.33.200 are not required if the adoptee is eighteen years of age or older. The section opens with the clause unless otherwise ordered by the court.

RCW 36.18.020 (superior court clerk filing fees and surcharges)

Sets a $200 fee for the first document in any civil action, naming an action for adoption expressly, then adds a $40 surcharge under subsection (5)(c) and a $50 surcharge under subsection (6). Last amended by 2025 c 357.

Regional Variances

Washington adult adoption rules at a glance

Who may be adopted

Any person, regardless of his or her age or residence (RCW 26.33.140(1)). No enumerated categories, no disability predicate, no former stepchild or foster requirement, and no bar on adopting a person who lives outside Washington.

Age relationship

None. Washington sets no minimum number of years and does not require the adoptee to be younger than the adopting adult (RCW 26.33.140(1)). The adopting adult must be legally competent and at least eighteen (RCW 26.33.140(2)).

Age of majority

Eighteen. All persons are of full age for all purposes at eighteen (RCW 26.28.010), and the adoption chapter defines a child as a person under eighteen years of age (RCW 26.33.020(6)).

Consent of the adoptee

Required, in writing and signed under penalty of perjury, because the statutory threshold is fourteen years of age or older (RCW 26.33.160(1)(a)). The executed consent is filed with the petition (RCW 26.33.150(3)).

The adopting person's spouse

Must join in the petition as a co-petitioner, which is more than consent (RCW 26.33.150(4)). No exception for separation, absence, incapacity or good cause appears in the chapter. A state registered domestic partner carries the same duty (RCW 26.33.902).

The adoptee's spouse

Not named in the consent list (RCW 26.33.160(1)). Every spousal reference in the adoption chapter concerns the petitioner's spouse. This is statutory silence rather than an express exemption, and attorney review of your own facts is available.

Birth parents

No consent and no notice. The consent clause reaches the parents and any alleged father only of an adoptee under eighteen years of age (RCW 26.33.160(1)(b)), and hearing notice runs only to those whose consent is required (RCW 26.33.240(1)).

Court and venue

Superior court, which the chapter adopts as its definition of court (RCW 26.33.020(7)). File in the county where the petitioner is a resident or where the adoptee is domiciled (RCW 26.33.030(1)). No durational residency period applies.

Filing fee

$290 in state set charges: a $200 base fee naming adoption expressly (RCW 36.18.020(2)(a)), a $40 surcharge (RCW 36.18.020(5)(c)) and a $50 surcharge (RCW 36.18.020(6)). Certified copies, service and publication are county set.

Reports and background checks

Not required once the adoptee is eighteen or older (RCW 26.33.220). The fingerprint based criminal history check and the child abuse registry review live inside the preplacement report (RCW 26.33.190(3)), so they fall away with it.

Federal statements and findings

Every petition under the chapter must allege whether the adoptee is or may be an Indian child and whether the federal Servicemembers Civil Relief Act of 2004 applies, and every decree must carry a finding on each (RCW 26.33.040(1), (2)).

Name change

Required decree content. The decree must state the full new name of the person adopted unless the name is not to be changed, alongside the full original name (RCW 26.33.250(1)). Names are exempt from the clear showing rule in RCW 26.33.250(2).

Inheritance

The adoptee becomes the child, legal heir and lawful issue of the adoptive parent with the right of inheritance and the right to take under testamentary disposition (RCW 26.33.260(1)). Issue reaches the adoptive parent's ancestors with no age qualifier (RCW 11.02.005(12)).

Forms

None statewide. The Administrative Office of the Courts states on its own forms site that adoption forms are not available on the Washington State Courts web site, so every document is drafted by the parties or taken from a county packet.

Suggested Compliance Checklist

Confirm Washington's two eligibility requirements

Before you draft anything days after starting

Verify you are legally competent and at least eighteen (RCW 26.33.140(2)). You do not need to check a category list, an age gap or the adoptee's residence, because any person may be adopted regardless of age or residence (RCW 26.33.140(1)).

Settle whether your spouse joins as a co-petitioner

Before the petition is drafted days after starting

If you are married or in a state registered domestic partnership, that person must join in the petition (RCW 26.33.150(4), RCW 26.33.902). Washington's chapter states no exception, so confirm your spouse will sign as a petitioner, not merely consent.

Draft the petition for adoption

First document to prepare days after starting

Include the four items in RCW 26.33.150(2) plus the Indian Child Welfare Act and Servicemembers Civil Relief Act statements required by RCW 26.33.040(1)(a) and (2). Washington publishes no statewide form. Attorney review of the petition is available through DocDraft.

Obtain the adoptee's written consent

Before filing days after starting

Prepare the written consent for the person being adopted, signed under penalty of perjury, and file it with the petition (RCW 26.33.160(1)(a), RCW 26.33.150(3)). No birth parent consent is needed once the adoptee is eighteen (RCW 26.33.160(1)(b)).

Draft the proposed decree of adoption

With the petition days after starting

Cover all six items in RCW 26.33.250(1), including the new name if one is wanted, and the findings on the Indian Child Welfare Act and the Servicemembers Civil Relief Act that RCW 26.33.040(1)(b) and (2) require in every decree under the chapter.

File the petition and pay $290

When the papers are signed days after starting

File in the superior court for the county where you are a resident or where the adoptee is domiciled (RCW 26.33.030(1)). Pay the $200 base fee plus the $40 and $50 surcharges (RCW 36.18.020(2)(a), (5)(c), (6)).

Request the hearing and attend it

After filing days after starting

No preplacement or post-placement report is required at eighteen or older, so ask the court to schedule the hearing (RCW 26.33.220, RCW 26.33.240(1)). The court enters the decree if the consents are valid and the adoption is in the adoptee's best interest.

Confirm the clerk sends the decree to vital statistics

After the appeal period expires days after starting

Once the time for appeal has run, the clerk transmits a certified copy of the decree to the state registrar of vital statistics (RCW 26.33.280). The registrar returns the decree if any item required by RCW 26.33.250 is missing (RCW 26.33.290(1)).

Frequently Asked Questions

Other Washington guides

Adverse Possession in Washington: Ten Years, or Seven If You Paid the Taxes

Asset Protection Planning in Washington (2026)

Dealing With Debt Collectors in Washington (2026)

Expunging a Criminal Record in Washington (2026)

Filing a Workplace Harassment Complaint in Washington

Filing Chapter 7 Bankruptcy in Washington (2026)

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