Trump account vs. UTMA: the math of a tax-free retirement head start

Fund a child's account young, convert it to a Roth, and let it compound tax-free. Here's exactly when that beats a taxable UTMA — and how the answer shifts with your return assumptions.

Families saving for a child today have three good tools, and they are not interchangeable. The trick is matching the tool to the job.

This article is about that third path. Trump accounts — the new child IRA created under the One Big Beautiful Bill Act — invite a direct comparison with the UTMA, because a family could fund either one with the same dollars in the same market. No deduction today for either contribution. The difference is the tax wrapper, and over a long horizon that difference compounds into real money. We work the math from the ground up, find the point where the Roth path overtakes the taxable one, and show how that point moves with your return assumptions.

The setup

We compare two accounts funded identically:

• Contributions: $5,000/year from age 3 through age 18 — 16 years, $80,000 of total contributions, which becomes cost basis inside each account. (A Trump account can receive contributions only until the year the child turns 18.)
• Growth rate: 10% annually in the base case (we test 5% and 15% later).
• The account then grows untouched — tax-deferred — until a Roth conversion at age 24, the point at which the child ages out of the kiddie tax.

At 10%, $5,000/year for 16 years grows to about $179,700 by age 18, and with six more years of compounding reaches roughly $318,400 by age 24 in either account. Same balance, same market. From here the two paths diverge entirely on taxes.

Path A — Trump account → Roth conversion at 24

A Trump account becomes a traditional IRA the year the child turns 18. At 24 we convert it to a Roth IRA to take advantage of likely low tax rates for your child as they start working. Because the $80,000 of contributions is already after-tax basis, only the earnings are taxed — for tax rates, we assume 22% federal + 8% state = 30% combined rate. After that, the account grows tax-free and can eventually be withdrawn completely tax-free.

Path B — UTMA, held and eventually sold

A UTMA is a taxable brokerage account. We assume a 1% dividend yield taxed each year at the same 30% (22% federal + 8% state), and that the position is eventually liquidated. Its $80,000 of contributions is also basis, so for long-term capital gains tax we assume 15% federal + 8% state = 23% and that applies only to the gain above that basis.

The accumulation phase

The future value of $5,000 contributed at the end of each year for 16 years at 10%, then grown six more years, is:

Of that, $80,000 is contributions (basis) and roughly $238,400 is earnings. Both accounts arrive at age 24 with the same balance.

The two strategies, in dollars

Let X = $318,400 be the age-24 balance and t the number of additional years of growth. Because the $80,000 basis is a fixed dollar amount — not a percentage — it does not cancel out, so we work in dollars.

The Roth strategy wins when Roth(t) ≥ UTMA(t). Solving numerically:

Roth advantage over UTMA, as a percentage. Below zero, the UTMA is ahead; above zero, the Roth wins. Break-even at age ~33.

The Roth strategy starts in a hole — paying the conversion tax up front means it begins with about $17,000 less working for it. But because only the gain is taxed and the conversion happens early, while the balance is still modest relative to the $80,000 basis, that hole is shallow and tax-free compounding fills it in about nine years.

How sensitive is this to returns?

Run the identical strategy at 5% and 15% growth and a clear — and slightly counterintuitive — pattern emerges:

Roth advantage over UTMA at three growth rates. Each line crosses zero at its own break-even age.

Higher growth pushes the break-even later, not earlier. The reason: at higher returns the gain is a larger share of the balance, so the up-front conversion tax is proportionally bigger — and the UTMA's ability to defer its tax to the end becomes more valuable. The Roth therefore takes longer to overcome its head start.

The crucial caveat is that this is a relative break-even, not an absolute one. In every scenario the Roth wins after the crossover and never gives the lead back, and the higher-growth cases produce far larger absolute dollars. A 15% world that breaks even at 42 still leaves the beneficiary decades of entirely tax-free compounding on a multi-million-dollar balance. The takeaway is simply that the Trump-to-Roth edge arrives soonest in modest-return environments and takes patience in spectacular ones.

The conversion is not a single push of a button

The base case assumes the entire gain is converted in one year at a 22% federal marginal rate. In practice it rarely works that cleanly, and two caveats matter.

These figures assume today's tax rates persist. The 22%/24% rate schedule was made permanent under the OBBBA, but "permanent" in tax law means "until Congress changes it." If ordinary rates rise, converting today's dollars to tax-free Roth looks even better; if they fall, the case softens. The capital-gains and state-rate assumptions are likewise fixed at today's levels.

A large conversion can push the beneficiary into a higher bracket — so you spread it out. A Roth conversion stacks on top of whatever else the young adult earns that year. For 2026, a single filer's 22% bracket tops out at $105,700 of taxable income; above that, the next dollars are taxed at 24% and beyond. Bracket thresholds are indexed to inflation, so by the time a 3-year-old today reaches the age-24 conversion — 21 years out — that 22% ceiling will have grown. At roughly 2.5% annual inflation indexing, $105,700 today becomes about $177,500 in 21 years.

Compare that ceiling to the taxable gain you'd be converting:

• At 5% growth, the ~$78,500 gain fits comfortably under the projected 22% ceiling — a one-year conversion is realistic if other earnings are below $100,000.
• At 10% growth, the ~$238,400 gain is roughly 1.3× the ceiling — plan on at least two years of conversions to keep the whole thing taxed at 22%, depending on the young adult's other earnings.
• At 15% growth, the ~$564,400 gain is over 3× the ceiling — realistically a four-to-five-year staged conversion depending on the young adult's other earnings.

Staging conversions across several low-income years — before the beneficiary's career earnings ramp up — is the standard technique, and it is what keeps the blended conversion rate near the 22% we assumed. A single-year conversion at exactly 22% is the idealized case; the multi-year version is how it will likely be done.

Assumptions

• Contributions: $5,000/year, ages 3–18 (16 years), $80,000 total basis, contributed at year-end.
• Growth: constant 10% annually in the base case; 5% and 15% shown for sensitivity. No investment guarantees a constant return.
• Accumulation taxes: we assume the child's unearned income during the accumulation years stays under the kiddie-tax threshold, so the accounts grow untaxed until the comparison begins at age 24. A small annual dividend tax during accumulation would modestly widen the Roth's advantage.
• Conversion: at age 24; tax applies to the earnings only (the $80,000 basis converts tax-free), at 22% federal + 8% state = 30%. Assumed at the 22% federal marginal rate, which in practice may require staging over multiple years.
• UTMA ongoing tax: 1% dividend yield taxed at 30% annually, modeled as a 0.30%/year growth drag.
• UTMA exit tax: 15% federal + 8% state = 23% long-term capital gains, applied to the gain above the $80,000 basis at liquidation.
• Tax rates assumed constant at current levels. 2026 single-filer 22% bracket ceiling of $105,700 projected forward at 2.5% annual inflation indexing.