California Adult Adoption: Requirements, Inheritance, and Limits

California adult adoption is a court process that creates a legal parent-child relationship between two adults. It is simpler than adopting a minor: no home study, no agency investigation, no need to terminate anyone’s existing parental rights. Two people sign an adoption agreement, file a short petition in superior court, appear before a judge, and if the judge approves, they are legally parent and child. The consequences, though, run deep, especially for inheritance, and some of them are permanent.

Who Can Adopt and Who Can Be Adopted

Family Code 9300 allows any adult to adopt another adult, including a stepparent adopting an adult stepchild.¹ A few conditions apply.

The adoptee has to be younger than the adopting parent. That is a statutory requirement under Family Code 9320, not a judicial preference.² The statute sets no minimum gap, but a small difference invites closer scrutiny from the judge about whether the relationship really reflects a parent-child dynamic. You cannot adopt your own spouse; the statute excludes that.

If the adoptee is married or has a registered domestic partner, that spouse or partner has to consent. The same goes for the adopting parent’s spouse. The rule exists so an adoption does not quietly reshape inheritance and property rights for someone else’s family.

The Adoption Agreement and Petition

Adult adoption is built around a written adoption agreement. Family Code 9320 requires both parties to sign a document stating that they voluntarily take on the legal relationship of parent and child, with all the rights and responsibilities that come with it.² The adoptee’s participation is fully voluntary; no one can be adopted against their will. The agreement itself is the proof of consent on both sides.

You file the petition in the superior court of the county where either party lives.³ Under Family Code 9321, the petition has to include:

How long you have known each other and the nature of your relationship.
Whether you are related by blood, and if so, how.
The reason you are seeking the adoption.
Why the adoption benefits both parties and the public.
Names and addresses of the adoptee’s living birth parents and any adult children.
Whether the adopting parent or their spouse has previously adopted another adult, with details.²

The main form is the Adoption Request, ADOPT-200, available on the California judicial branch website.⁴ You will also need a proposed adoption agreement and a proposed order. Some counties ask for additional documents, so call the clerk before filing.

The filing fee is $20.³ A fee waiver is available if you receive public benefits, earn below a set income threshold, or cannot pay without sacrificing basic needs. Hiring an attorney is optional; those who handle these cases typically charge $1,500 to $3,500.

The Court Hearing

Once the petition is filed, the clerk schedules a hearing. Both parties have to appear in person unless the court specifically allows otherwise.² The judge may question each of you about the relationship and your reasons.

Under Family Code 9328, the judge approves the adoption only if satisfied it serves the best interests of both parties and the public interest. The court can consider any evidence, written or oral, and is not bound by the usual rules of evidence. A judge who suspects fraud, financial manipulation, or coercion will deny the petition.²

One real advantage over child adoption: no agency investigation is required. The court has the option to order one from a probation officer or state department, but most adult adoptions proceed without it. Processing time varies by county, from a few weeks to a few months.

Inheritance Rights Gained and Lost

Inheritance is the most common reason people pursue adult adoption, and it is where the stakes are highest. Once the adoption is final, the adoptee has the same inheritance rights as a biological child. Under Probate Code 6450, a parent-child relationship exists between an adopted person and the adoptive parent for intestate succession, so if the adoptive parent dies without a will, the adoptee inherits as a biological child would.⁵

Here is what catches people off guard. The adoption usually severs the inheritance relationship with the adoptee’s biological parents. Under Probate Code 6451, once you are adopted you generally lose the right to inherit from your birth parents, and they lose the right to inherit from you.⁶ A narrow exception preserves the biological inheritance link if the birth parent and adoptee previously lived together as parent and child and the adoption was by a stepparent or occurred after the birth parent died. Outside those situations, the severance is complete.

An adoptee who expects to inherit from both a biological parent and an adoptive parent can end up cut off from the biological parent’s estate entirely. Review both sides of the inheritance equation with an estate planning attorney before filing.

Other Legal Effects

Adult adoption establishes legal next-of-kin status. Depending on the circumstances, the adoptee may gain authority to make medical decisions for the adoptive parent during incapacity, and vice versa. It can also affect Social Security survivor benefits and eligibility for benefits tied to the adoptive parent’s employment or veteran status, though each program has its own qualifying rules.

If the adoptee is under 26, they can be added to the adoptive parent’s health insurance plan, since federal law treats adopted children the same as biological children for dependent coverage up to that age.⁷

A name change is not automatic. If the adoptee wants to take the adoptive parent’s surname, that may require a separate petition under Code of Civil Procedure 1276, filed in the superior court of the county where the adoptee lives.⁸

What Adult Adoption Does Not Do

No Immigration Benefit

This is the most misunderstood piece, and getting it wrong can lead to criminal prosecution. Under federal immigration law, an adopted person only qualifies as a “child” if adopted before age 16 and after living with the adoptive parent for at least two years.⁹ A U.S. citizen can petition for an adopted “son or daughter” who is now over 21, but only if the person met the child definition at the time of adoption, meaning the adoption happened before age 16.¹⁰

Adopting an adult in California state court does nothing to create immigration eligibility. USCIS has stated this explicitly: adult adoptees who were not adopted as children under immigration law do not gain a path to citizenship or a green card through adoption.¹¹ Encouraging someone to enter or remain in the United States illegally based on false promises about adult adoption can bring federal criminal charges carrying up to five years in prison, or ten years if done for financial gain.

No Adoption Tax Credit

The federal Adoption Tax Credit is limited to adopting a child who is under 18 or physically or mentally unable to care for themselves.¹² Adopting a healthy adult produces no federal tax benefit from the adoption itself. Claiming the adoptee as a dependent is governed by the ordinary dependency rules: the adoptee generally must live with you, earn below the income threshold, and depend on you for more than half their support. The adoption supplies the family relationship, but the income and support tests are the hard part for most financially independent adults.

Not Easily Reversed

Adult adoption is intended to be permanent. The annulment process under Family Code 9100 is written for child adoptions involving an undisclosed developmental disability or mental illness that existed before the adoption, and it requires filing within five years. No dedicated reversal statute exists for adult adoption. A court can sometimes vacate an adoption order on grounds like fraud or duress using its general equitable powers, but that is rare. Treat an adult adoption as irreversible when you decide whether to go forward.

1
California Legislative Information. California Code FAM 9300 – Adoption of Adults and Married Minors
2
California Legislative Information. California Code Family Code – Procedure for Adult Adoption
3
California Courts. Adult Adoption in California
4
Judicial Branch of California. Adoption Request (ADOPT-200)
5
California Legislative Information. California Code Probate Code 6450 – Parent and Child Relationship
6
California Legislative Information. California Code Probate Code 6451 – Natural Parent and Child Relationship
7
HealthCare.gov. Health Insurance Coverage For Children and Young Adults Under 26
8
California Legislative Information. California Code of Civil Procedure 1276 – Application for Change of Name
9
U.S. Department of State. 9 FAM 502.3 – Classification of Immigrants Under INA
10
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 5, Part E, Chapter 2 – Eligibility
11
U.S. Citizenship and Immigration Services. Adult Adoptees and U.S. Citizenship
12
Internal Revenue Service. Adoption Credit