This is a common question from parents whose children are legally adults but, realistically, are still early in adulthood. And the answer is: it depends.
Yes, in California anyone over 18 is legally old enough to serve as successor trustee. That does not mean they are the right person for the job.
Many parents assume naming a child is the natural choice. They trust them, they want to keep things in the family, and their child may be smart, responsible, kind, or “mature for their age.” But being a trustee is not an honorary title or a family favor. It is a real legal job, with real legal obligations and real consequences if the trustee gets it wrong.
A trustee is a fiduciary. That means the California law imposes serious duties on them, including acting in the beneficiaries’ interests, following the trust terms, keeping accurate records, providing information and accountings when required, avoiding conflicts of interest, and prudently managing trust assets. Beneficiaries can challenge trustee actions and, in some situations, sue the trustee personally. In other words, this is not just an internal family project.
What Would Your Child Actually Need to Do?
A trustee is the single person in charge of administering the trust. That may mean hiring and managing attorneys, accountants, financial advisors, real estate agents, or other professionals, and figuring out which professionals are actually competent and appropriate for the situation. It may mean dealing with banks, gathering assets, handling taxes, maintaining records, making distribution decisions, and communicating clearly with beneficiaries who may be grieving, impatient, entitled, suspicious, or simply disagree with each other.
Sometimes the hardest part of being a trustee is not the paperwork—it is managing people. Can your child handle pressure from a sibling demanding an early distribution? Can they explain why something cannot happen yet? Can they stand up to unreasonable demands and, when necessary, tell people no?
If the trust assets are not being distributed immediately, the job may continue for years. During that time, the trustee may be responsible for managing and investing trust assets, either directly or by hiring competent professionals to help. If you would like a fuller explanation of trustee responsibilities, see my article on The Role of the Successor Trustee After Settlor(s) Death.
“But My Child Is Very Mature”
Maybe. But when parents say this, I encourage them to think about the actual responsibilities above.
Being intelligent is not the same thing as being prepared for fiduciary responsibility. Being kind is not the same thing as being able to manage conflict. Being organized is not the same thing as being able to choose and supervise competent professionals.
Ask yourself: has your child ever hired a lawyer, worked with a CPA, negotiated with a bank, made significant financial decisions, managed a complicated multi-step project, handled emotionally charged family conflict, or told someone “no” when money was involved?
A good trustee does not need to know how to do everything personally. In fact, a good trustee should hire professionals when appropriate. But even doing that well requires judgment, confidence, follow-through, and real-world adult experience.
The Age Question
There is no magic age. Some people in their twenties would make excellent trustees, and some much older adults would be terrible at it.
But if your proposed trustee is somewhere in the 18–30 range, the question deserves serious thought. Many young adults are still building careers, moving cities, getting married, having children, figuring out finances, and learning how adult systems actually work. The issue is not just whether they are capable. It is whether they realistically have the bandwidth, judgment, and life experience to take on an additional serious legal responsibility at that stage.
“We Want to Keep It in The Family”
I hear this often, and sometimes that makes sense. But “keeping it in the family” is not the goal. Competent trust administration is the goal.
Depending on your circumstances, alternatives may include another relative, a trusted friend, a professional fiduciary, or a corporate trustee. Yes, professionals cost money. But so do trustee mistakes, litigation, and damaged family relationships. A family member is not automatically the best choice simply because they are family.
Bottom Line
If your young adult child is genuinely capable, emotionally steady, organized, comfortable managing professionals, and able to handle both money and people, naming them as successor trustee may be entirely appropriate.
If they are legally adults but have not yet developed those skills—or simply do not have the capacity to take this on—another choice may be wiser.
Estate planning is not about choosing the person you love the most. It is about choosing the person most capable of doing the job. And if you are unsure whom to name as a successor trustee – I’d be happy to discuss it with you and help you make that important decision.
Set up a free consultation today