Yes, an 18-year-old can be adopted. It’s called adult adoption, and in most states it’s considerably simpler than adopting a minor: no home study, no investigation into parental fitness, and no termination of biological parental rights, because those rights no longer apply once someone reaches the age of majority. Once a judge signs the decree, the adoptee becomes the adopting parent’s legal child for inheritance, decision-making, and every other purpose the law recognizes.
Why Adopt an Adult
Inheritance is the most common reason. A legally adopted adult is treated identically to a biological child under intestate succession, so they inherit automatically if the adoptive parent dies without a will. A stepchild, foster child, or long-term family member without an adoption has no default inheritance rights and would have to be named specifically in estate documents that biological relatives can contest.
Formalizing a stepparent or foster parent relationship is another frequent motivation. Many people grow up raised by a non-biological parent but never had a legal adoption completed during childhood. Adult adoption gives that relationship legal recognition, which matters for hospital visitation, medical decision-making, and the significance of having the bond acknowledged on paper.
Adult adoption also creates a legal framework for the lifelong care of an adult with a disability, giving the adoptive parent standing to make healthcare and financial decisions. Before marriage equality, same-sex couples sometimes used adult adoption when no other legal recognition was available, and some of those adoptions remain in effect today.
State Rules Can Restrict Who Qualifies
Most states permit adult adoption, but the rules vary and a handful impose real limits. Some states allow it only when the adoptee has a disability or intellectual disability. Others restrict it to situations where a prior family relationship already exists, such as a stepparent or foster parent bond that lasted a minimum number of years. A few require the adoptee to have lived in the adopting parent’s home for a continuous period, often two or more years, before a petition can be filed.
Some states go further and permit adult adoption only among relatives like nieces, nephews, cousins, or grandchildren, or between former foster parents and foster children who kept a continuous relationship. Others prohibit adoption between spouses or certain close blood relatives. Because these rules differ so much, check your state’s adoption statute before you start.
Consent and Other Eligibility Rules
Both the adopting parent and the adult being adopted must voluntarily agree to the adoption in writing. Because the adoptee is a legal adult, biological parents have no say. Their parental rights aren’t “terminated” the way they would be in a child adoption; they simply no longer apply. A few states do require that biological parents receive notice, even though their consent isn’t needed.
If either party is married, many states require the spouse to consent in writing, since adoption changes inheritance rights and creates new legal obligations that affect a spouse’s financial interests. A court can sometimes waive this requirement if a spouse is incapable of consenting or if the couple is legally separated, but in most jurisdictions you should expect to need the signature.
Many states also require the adopting parent to be a certain number of years older than the adoptee. Ten years is the most common threshold, though some states set different minimums or leave it to the judge. The requirement is meant to ensure the adoption resembles a genuine parent-child relationship rather than a legal arrangement between peers.
What you won’t face is a home study or fitness investigation. Courts treat the adoptee as capable of deciding whether the adoption serves their own interests, which is the single biggest reason adult adoption is faster and cheaper than child adoption.
How the Process Works
The adoption begins with a Petition for Adoption filed in the appropriate court, usually in the county where one of the parties lives. Many county courts post the required forms on their websites. The petition asks for identifying information about both parties: full legal names, dates and places of birth, current addresses, the names of the adoptee’s biological parents, and the nature of the relationship between the adopting parent and the adoptee.
Along with the petition, you file separate consent forms signed by the adoptee, the adopting parent, and any spouses whose consent is required. Some courts require these to be notarized. You’ll also typically need a certified copy of the adoptee’s original birth certificate. Filing fees vary but generally run a few hundred dollars. If you hire an attorney, expect roughly $1,000 to $2,000 on top of the filing fee for a straightforward case; contested or complex situations cost more.
Most adults handle uncomplicated adult adoptions without an attorney. Where things get complicated, such as significant assets, an existing trust, or a blended-family dispute, professional legal advice is worth the cost. Mistakes in the paperwork can delay a case by months.
Once the petition is filed and the fee paid, the clerk schedules a hearing. Adult adoption hearings tend to be brief. The judge confirms identities, verifies that consent is genuine and voluntary, and in some jurisdictions considers whether the adoption serves the interests of both sides. If everything checks out, the judge signs the final order or decree of adoption and the legal parent-child relationship takes effect immediately.
Judges do watch for red flags. A court may take a closer look at an adoption that appears designed to manipulate inheritance from a third party’s estate, circumvent immigration law, or formalize a romantic relationship rather than a parent-child one. These situations don’t automatically disqualify an adoption, but they invite scrutiny.
What Changes After the Decree
The biggest legal consequence is inheritance. Once the adoption is final, the adoptee inherits from the adoptive parent exactly as a biological child would. If the adoptive parent dies without a will, the adopted adult stands in line with any biological children. The reverse also applies: the adoptive parent can inherit from the adopted adult.
The flip side is that adult adoption typically severs the adoptee’s legal inheritance rights from their biological parents. If a biological father dies without a will after his adult child has been adopted by someone else, the adoptee may have no claim to the estate. A small number of states let adopted adults retain inheritance rights from both biological and adoptive families, but this is the exception. Think carefully about what biological inheritance rights you might be giving up before moving forward.
Practical paperwork follows the decree. The adoptee can apply to the birth state’s vital records office for a new birth certificate; some states issue an entirely new one listing the adoptive parent, while others only change the surname. If the adoption includes a name change, notify the Social Security Administration using Form SS-5 to update the card,1Social Security Administration. How Do I Change or Correct My Name on My Social Security Number Card and submit the adoption decree with any passport application to explain the name change.2U.S. Department of State. Foreign Affairs Manual – Name Usage and Name Changes Court records in adoption cases are sealed in most states, so the underlying petition and consent forms are not part of the public record.
What Adult Adoption Won’t Do
Adult adoption does not create a path to U.S. citizenship or a green card. Federal immigration law defines a “child” for visa sponsorship purposes as someone adopted before age 16, or before age 18 in limited sibling cases.3Office of the Law Revision Counsel. 8 USC 1101 – Definitions A U.S. citizen cannot file a family-based immigration petition (Form I-130) for someone adopted after age 16 unless the adoptee lived in the petitioner’s legal custody for at least two years before filing.4U.S. Citizenship and Immigration Services. Instructions for Form I-130, Petition for Alien Relative The Child Citizenship Act of 2000 applies only to children who meet its requirements before turning 18.5U.S. Citizenship and Immigration Services. Adult Adoptees and U.S. Citizenship Adopting someone at 18 to sponsor them for immigration will not work under current law.
Most federal dependent benefits are also off the table. An adopted adult can qualify for Social Security survivor benefits only in narrow circumstances, generally when they have a disability that began before age 22.6Social Security Administration. Who Can Get Survivor Benefits Veterans can claim adopted children as dependents only if the child is under 18 (or under 23 and enrolled in school), or became permanently disabled before turning 18.7Veterans Affairs. Manage Dependents for Disability, Pension, or DIC Benefits A healthy adult adopted at 18 does not create dependent status for VA purposes.
Reversing an Adult Adoption
Adult adoptions can be reversed, though it’s uncommon and never automatic. Reversal requires a formal petition, supporting documents including the original decree, and a hearing where a judge decides whether to grant the annulment. Courts are more likely to reverse an adoption obtained through fraud, duress, or undue influence. Either party can petition. Undoing the adoption also undoes the inheritance rights, the legal parent-child status, and any name changes that came with the original decree.