You can’t open a true joint brokerage account with a child. Minors don’t have the legal capacity to sign binding financial contracts in any U.S. state, so brokerages won’t list a person under 18 as a co-owner on a standard joint account. The workaround the industry uses is a custodial account under the Uniform Gifts to Minors Act (UGMA) or the Uniform Transfers to Minors Act (UTMA), where you manage the investments and the child owns them.
Why a Joint Account With a Minor Isn’t Allowed
A standard joint brokerage account gives every account holder equal ownership and full authority to buy, sell, deposit, or withdraw. Each co-owner can independently direct trades and drain the account. That arrangement requires every party to have the legal capacity to enter a binding contract, and minors don’t have it. A contract signed by someone under 18 is generally voidable at the minor’s option, which means the child could later disavow the account agreement and potentially unwind trades. No brokerage will accept that risk, and no adult co-owner should either.
This isn’t a policy quirk you can shop around. It’s a structural legal limitation, which is why the custodial account exists.
What a Custodial Account Actually Is
A custodial account under UGMA or UTMA is not jointly owned. An adult custodian holds legal title and manages the investments; the child holds beneficial title as the irrevocable owner of every dollar in the account. The adult drives, but the child’s name is on the title. You pick the investments, place the trades, and handle the paperwork. The child owns the result.
Every contribution is a permanent, irrevocable gift. Once money goes in, you can’t take it back, redirect it to another child, or reclaim it if your own finances change. The assets are legally separated from your personal estate. This is the single biggest difference from a joint account, and it catches many parents off guard.
UGMA vs. UTMA
UGMA accounts hold financial assets: cash, stocks, bonds, and mutual funds. UTMA accounts can hold all of those plus real estate, patents, royalties, and other non-financial property.1Cornell Law School. Uniform Gifts to Minors Act (UGMA) Nearly every state has adopted the UTMA framework, which replaced the older UGMA, though a few states still operate under UGMA rules. The state law where the account is opened controls what assets are allowed and when the child gains full control.
What You Can and Can’t Do as Custodian
You have a fiduciary duty to invest the account’s assets using a prudent investor standard, meaning every decision has to be made for the child’s benefit with reasonable care and skill.2Uniform Law Commission. Uniform Transfers to Minors Act Self-dealing is prohibited. You can’t borrow from the account, use it as collateral for your own debts, or invest in something that benefits you at the child’s expense.
Withdrawals before the child reaches the age of majority are limited to expenses that directly benefit the child and don’t overlap with basic parental obligations. You generally cannot use the funds for food, shelter, clothing, or other necessities you’re already required to provide. Enrichment programs, specialized tutoring, or a computer for school are more defensible. Document any withdrawal with receipts showing how the money was spent for the child, because misusing custodial funds can expose you to personal liability.
How the Account Is Taxed
Investment income inside a custodial account belongs to the child, but the IRS won’t let families shift unlimited investment income into a child’s lower tax bracket. The “Kiddie Tax” rules apply to unearned income (interest, dividends, and capital gains) received by children under 18, children who are 18 and don’t earn more than half their own support, and full-time students under 24 who don’t earn more than half their own support.3Internal Revenue Service. Topic No. 553, Tax on a Child’s Investment and Other Unearned Income (Kiddie Tax)
For 2026, the tax works in three tiers:4Internal Revenue Service. Revenue Procedure 2025-32 – Section 4.02
- The first $1,350 of unearned income is tax-free, matching the standard deduction for a dependent with unearned income.
- The next $1,350 (up to $2,700) is taxed at the child’s own rate, usually 10%.
- Anything above $2,700 is taxed at the parents’ marginal rate, which can run as high as 37%.
Long-term capital gains and qualified dividends keep favorable rate treatment, but the applicable rate is the parents’ capital gains rate, not the child’s. That largely wipes out the tax benefit of parking a big investment balance in a child’s name. In practice, custodial accounts work best for growth-oriented investments that defer taxable income until the child is an adult and no longer subject to the Kiddie Tax.
Contributions Are One-Way Gifts
Every dollar you put into a custodial account is a completed, irrevocable gift. Unlike a 529 plan, where the account owner can change the beneficiary, custodial account contributions permanently belong to the specific child named on the account.
For 2026, you can give up to $19,000 per recipient without any gift tax filing requirement, and a married couple can jointly give $38,000 to a single child.5Internal Revenue Service. What’s New – Estate and Gift Tax – Section: Annual Exclusions Above those thresholds, you file Form 709 to report the excess even if no tax is owed. Actual gift tax is rare; the point is that the money is gone from your control the moment it lands in the account.
What Happens When the Child Turns 18 or 21
Your authority as custodian ends automatically when the child reaches the termination age set by state law. For UGMA accounts, that’s typically 18. Under UTMA, it’s often 21, though some states allow the transferor to specify an age as late as 25.6Social Security Administration. POMS SI SEA01120.205 – The Legal Age of Majority for Uniform Transfer to Minors Act (UTMA) The termination age has to be chosen when the account is opened and can’t be changed later.
At that age, the brokerage converts the account into a standard individual account in the young adult’s name. It isn’t a taxable event, because the child was already the beneficial owner. After the transfer, you have zero authority over the assets, and the young adult has unconditional control. They can sell everything and spend the proceeds however they choose. There is no mechanism to delay the handoff, impose conditions, or claw back funds if you disagree with the outcome.
That’s the trade-off for the simplicity of a custodial account. Parents who aren’t comfortable with a fixed handover date often prefer a trust, which can spell out specific terms and conditions for distributions, though trusts cost more to create and maintain.
Side Effects Parents Often Miss
Financial Aid
On the Free Application for Federal Student Aid (FAFSA), custodial account balances count as the student’s assets, not the parents’. The federal formula assesses student-owned assets at 20% per year, so a $50,000 custodial account could reduce a financial aid package by $10,000 annually. Parent-owned assets, by contrast, are assessed at a maximum of roughly 5.64%. A parent-owned 529 plan gets the favorable parent-asset treatment even when the child is the designated beneficiary. If need-based aid is likely to matter for your family, this alone often tips the choice away from a custodial account.
Means-Tested Benefits
For a child receiving Supplemental Security Income (SSI), a custodial account can be a serious problem. The SSI resource limit is $2,000.7Social Security Administration. Understanding Supplemental Security Income SSI Resources – 2025 Edition While a UTMA balance may not count as an available resource while the child is still a minor, the full amount becomes a countable resource when the child reaches the state’s termination age, which can immediately disqualify a young adult from SSI and, in many states, Medicaid. If your child receives or may need means-tested benefits, talk to a special needs planning attorney before opening or funding one of these accounts.
Custodial Account or 529 Plan?
Parents looking at custodial accounts are usually weighing them against a 529 college savings plan. They solve different problems:
- A 529 plan’s earnings grow tax-free, and qualified education withdrawals are tax-free. Custodial account earnings are taxable every year under the Kiddie Tax rules.
- A 529 limits you to the plan’s investment menu, usually a set of mutual fund portfolios. A custodial account can hold individual stocks, bonds, ETFs, mutual funds, and (under UTMA) non-financial assets.
- A 529’s tax benefits attach to qualified education expenses, including tuition, room and board, and up to $10,000 per year for K-12 tuition. Custodial funds can be used for anything once the child takes control.
- A parent-owned 529 is assessed on the FAFSA at up to 5.64%. A custodial account is assessed at 20%.
- A 529 owner keeps control and can change beneficiaries. Custodial contributions are irrevocable gifts to one specific child.
If the goal is funding college, a 529 is usually the stronger tool. If you want the child to have a broader investment account not tied to education, a custodial account fits better. Some families run both: a 529 for tuition and a smaller custodial account to teach the child about investing with real money.