What Happens to Child Custody When Children Turn 18 in California?

By Andrew M. Meinzer

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Child Custody

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Last Modified on Sep 08, 2026

For many California parents, a child’s 18th birthday is an exciting transition. However, you may be wondering what happens to child custody when children turn 18 in California. This age is also an important legal milestone. Family court custody orders generally end when a child becomes a legal adult, which means they have the authority to decide where they live and make medical, financial, and other personal choices.

Your child’s transition into adulthood also makes a difference for your estate plan. Your priorities may change, from setting up a guardianship plan to making your property available for your children. You may also want to talk to your children about financial and legal tools they may wish to establish. Furthermore, if your child has special needs, estate planning tools can help you provide them with continued support even when you do not have custody.

What to Know About Adjusting Your Estate Plan After Your Child’s 18th Birthday

Estate plans are not meant to be created and then left alone. A child’s 18th birthday is a good time to review and update your estate plan. Surveys show that 62% of Americans have updated their estate plan within the last six months to five years.

No longer having custody of your child can bring large financial changes, changes in your legal authority, and may make you want to adjust how you plan on distributing your assets. After your child turns 18, you may want to:

• Update your will or trust if you would like to change what assets your child is going to inherit
• Review beneficiary designations of life insurance policies and retirement accounts
• Consider naming your adult child as a successor trustee, executor, or agent under a power of attorney
• Review guardianship or special needs planning if your child has special needs

Important Tools for Adult Children With Special Needs

For families with adult children who have disabilities, turning 18 and losing child custody does not always look the same as other families. You may still be your child’s caregiver or be there to help manage their financial affairs. However, without child custody, you must use special needs planning tools to establish this legal authority.

About one in four adults has a disability, though this looks different for each person. Depending on an individual’s needs, certain legal tools may offer better advantages. Some common tools include:

• Supported decision-making arrangements: Supported decision-making allows adults with special needs to make their own decisions while receiving assistance and guidance from trusted individuals, such as parents or counselors.
• Durable powers of attorney: This tool allows your child to appoint someone they trust to handle certain financial or legal matters on their behalf.
• Conservatorship: A conservatorship is a court-supervised arrangement that allows a conservator to make certain decisions on behalf of an adult who cannot manage their affairs on their own.
• A special needs trust: A special needs trust can be used to transfer property to a disabled child while still preserving their eligibility for certain government benefits.

What 18-Year-Olds Should Consider When it Comes to Estate Planning

While it may seem unnecessary to create an estate plan as a young adult, unexpected accidents and illnesses can happen at any age, and having the proper documents in place can make it easier for families to provide assistance when needed. In the United States, 12% of the population is between 18 and 24, meaning they may benefit from certain estate planning tools.

Some young adults choose to sign an advance healthcare directive or create a durable power of attorney that can allow someone to make medical and financial decisions if they become incapacitated. Additionally, young adults with significant assets or children may benefit from creating a will.

Hire a Child Custody Lawyer From Meinzer Law Firm, PC

At Meinzer Law Firm, PC, a compassionate California child custody attorney is prepared to guide you through the changes in your child custody case as your child reaches age 18. We know this transition can be difficult, which is why we seek to set you up with the legal tools you need for a smooth transition, both for you and your future, and your child’s. We bring over 25 years of legal experience as estate planning lawyers to every case and have helped countless families with minor and adult children.

FAQs

Can an 18-Year-Old Decide Which Parent to Live With in California?

Yes, once a child turns 18, California’s child custody laws allow them to decide where they want to live, and the outcome of an earlier child custody case does not apply. This may mean deciding to live on their own, with one parent, or splitting time between both parents, depending on financial means, parents’ preferences, and the child’s preferences. Where a child decides to live can impact your everyday life and financial situation.

Do Parents Have the Right to Make Medical Decisions After a Child Turns 18?

No, parents generally do not have the right to make medical decisions after a child turns 18. After this age, your child can keep their medical records private and make their own decisions. However, tools such as an advance health care directive or HIPAA authorization can be set up to allow an adult child to name adults who can assist if they are unable to make medical decisions.

Can You Name Your Child as Your Executor Once They Turn 18?

Yes, if your child turns 18 and has the capacity to serve as an executor, you can name them as the executor in your will. However, you should consider whether they are financially responsible, organized, and prepared to handle these responsibilities. If you do want to update your will, you should hire a child custody lawyer to make the appropriate changes to your estate plan.

What Is a Special Needs Trust?

A special needs trust is a type of trust where you can pass on assets to an individual with a disability. The benefit of using this type of trust is that it does not jeopardize their eligibility for certain government benefits, such as Medicaid or Supplemental Security Income (SSI).

Learn How Meinzer Law Firm, PC, Can Help

Watching your child become an adult can be exciting, but it is also nerve-wracking to think about losing custody. Contact Meinzer Law Firm, PC, to learn about your legal options throughout and after this transition.