529 plan vs. custodial account: how to invest for your children

Basics8 min read · updated 2 November 2026 · 7 sources

Parents and grandparents who want to invest for a child in the US usually choose between two accounts. A 529 plan grows tax-free as long as the money pays for education. A custodial account under UTMA or UGMA can be used for anything, but it belongs to the child and is taxed partly at the parents' rate. This article compares both with the rules for 2026, from K-12 tuition and the new Roth IRA rollover to the kiddie tax and financial aid.

How a 529 plan works

A 529 plan, officially a qualified tuition program, is sponsored by a state or an educational institution. Contributions are not deductible on the federal return, but the earnings grow tax-free and are not taxed when they are spent on qualified education expenses (IRS Topic 313 2026). Many states give a state income tax deduction for contributions to their own plan, so the home state's plan is often the first one to compare. You can usually choose among age-based portfolios that shift from stocks to bonds as college approaches, and static portfolios.

Qualified expenses include tuition, fees, books and, within limits, room and board at eligible colleges and universities. For school before college, the limit for K-12 tuition rose from $10,000 to $20,000 per year and beneficiary starting in 2026 (IRS Topic 313 2026).

Money that is withdrawn for something else costs more. The earnings part of a nonqualified withdrawal is taxable as income and usually carries an additional 10% tax. Exceptions apply, for example, if the beneficiary receives a tax-free scholarship, becomes disabled or dies (IRS, 529 technical guide 2024). The contributions themselves come back without tax, because they were made with taxed money.

What happens to leftover money

Two rules make the fear of overfunding smaller than it used to be. First, the account owner can usually name another family member as the new beneficiary, for example a younger sibling. Second, since 2024 the beneficiary can move money from a 529 plan into a Roth IRA without tax, if the account has existed for at least 15 years, the transfer goes directly between the providers, it stays within the annual Roth IRA limit and a lifetime maximum of $35,000, and the money does not come from contributions of the last five years (IRS Topic 313 2026).

With the 2026 IRA limit of $7,500 (IRS retirement plan limits 2025), reaching the $35,000 takes several years of transfers. Because each transfer counts toward the annual Roth IRA limit, the beneficiary also needs earned income at least equal to the amount. For a child whose education turned out cheaper than planned, it is a useful way to turn the remainder into retirement savings instead of paying the 10% additional tax.

Gifts and superfunding

A contribution to a 529 plan counts as a gift to the beneficiary. In 2026, each person can give $19,000 per recipient without using any of the lifetime gift and estate tax exemption (Rev. Proc. 2025-32 2025, sec. 4.42). For 529 plans there is a special rule: a contribution above the annual exclusion can be treated as made evenly over five years (IRS, 529 technical guide 2024). Grandparents use this to move a larger amount out of their estate at once.

Custodial accounts: UTMA and UGMA

A custodial account under the Uniform Transfers to Minors Act (UTMA) or Uniform Gifts to Minors Act (UGMA) is a brokerage account in the child's name, managed by an adult until the child reaches the age set by state law, usually 18 or 21. The gift is irrevocable: the money belongs to the child and can be used for anything that benefits them, and at the age of majority the child gets full control.

Investment income in the account is the child's income, but the kiddie tax limits the advantage. For 2026, the first $1,350 of unearned income is covered by the dependent's standard deduction, the next $1,350 is taxed at the child's rate, and unearned income above $2,700 is taxed at the parents' rate (Rev. Proc. 2025-32 2025, sec. 4.02). A custodial account therefore suits moderate amounts; above a few thousand dollars of yearly dividends and gains, the tax advantage over the parents' own account disappears.

Financial aid: who owns the account matters

For federal student aid, the Student Aid Index counts a 529 plan owned by a parent among the parents' investments. Parents' net worth enters the formula at a conversion rate of 12%, and only part of that ends up in the index; the assets of a dependent student enter at 20% (Federal Student Aid 2025). A custodial account belongs to the child and is therefore counted as the student's asset. For families that expect to qualify for aid, a parent-owned 529 plan is usually the better choice.

529 plan or custodial account: the comparison

What research shows

Starting early matters more than the account type. In a randomized experiment, every newborn in a sample from an entire state received a college savings account with an automatic initial deposit. Seven years later, Clancy et al. (2016) found a large effect on assets for college, mostly from the automatic deposit and its investment earnings, and concluded that deposits made early and held in an investment have the greatest influence. The mechanics are those of compound interest: every year of delay costs growth that later contributions cannot replace.

A related observation from retirement saving applies here too: default settings stick. Once an automatic monthly contribution is set up, most people keep it, which is the main reason it works (Madrian and Shea 2001).

Common mistakes

• Choosing only by state tax deduction: high fees in the home state's plan can outweigh a small deduction over 18 years.
• Staying too aggressive near college: money needed in two years should not sit fully in stocks; age-based portfolios handle this automatically.
• Putting large sums in a custodial account: the kiddie tax applies above $2,700, the child gets control at 18 or 21, and aid formulas count it heavily.
• Forgetting K-12 and Roth options: since 2026 up to $20,000 a year of K-12 tuition qualifies, and leftovers can partly move into a Roth IRA.
• Withdrawing for non-education expenses without need: the earnings then cost income tax plus 10%.

This article explains general federal rules and is not tax or legal advice. State tax treatment of 529 plans differs; check your plan's documents and your state's rules.

This article explains a method; it is not investment or tax advice. Worked examples are simplified and rounded. All terms in the glossary.