# UTMA Calculator

UTMA calculator that projects a custodial account balance at the age of majority. Includes S&P 500 growth assumptions and kiddie tax estimates.

## What this calculates

A UTMA calculator projects how much a custodial account under the Uniform Transfers to Minors Act will be worth when your child reaches the age of majority. Enter the current balance, monthly contributions, expected return, and the beneficiary's current age to see the projected handoff value plus an estimate of the annual kiddie tax drag.

## Inputs

- **Current UTMA Balance** ($) — min 0 — Balance today in the custodial account.
- **Child's Current Age** — min 0, max 21 — The beneficiary's current age.
- **Age of Majority in Your State** — min 18, max 25 — When the account transfers to the beneficiary. 18 in CA and many states, 21 in NY and most UTMA states, up to 25 in a few.
- **Monthly Contribution** ($) — min 0 — Amount the custodian deposits each month.
- **Expected Annual Return** (%) — min 0, max 25 — The S&P 500 has averaged about 10% nominal (7% after inflation) over the long run. Use 7% for real (inflation-adjusted) dollars.
- **Annual Unearned Income on Account** ($) — min 0 — Interest, dividends, and realized gains the account generates each year. Used to estimate kiddie tax exposure.

## Outputs

- **Projected Balance at Age of Majority** — formatted as currency — Estimated account value when control transfers to the beneficiary.
- **Total Contributions** — formatted as currency — Sum of starting balance plus monthly contributions.
- **Investment Growth** — formatted as currency — Earnings from compounded returns.
- **Years Until Handoff** — Years until the custodianship ends and the beneficiary takes control.
- **Estimated Annual Kiddie Tax** — formatted as currency — Rough annual federal kiddie tax on unearned income above the 2024 $2,600 threshold, at a 24% parent rate.

## Details

## What a UTMA account is

A UTMA (Uniform Transfers to Minors Act) account is a custodial brokerage or bank account held in a child's name with a parent or relative as custodian. The adult manages the assets until the beneficiary reaches the age of majority (18, 21, or up to 25 depending on state). At that point, the account transfers irrevocably to the beneficiary, who can use the funds for anything, not just college.

## The math this UTMA calculator uses

This is a monthly compound interest model. Balance at handoff = current balance times (1 + r/12)^(12 x years) plus the future value of the monthly contribution annuity. With $5,000 starting balance, $200 monthly, 16 years to majority, and 10% annual return, the projected balance is about $119,000. Of that, $43,400 is your contributions and roughly $75,400 is investment growth.

## UTMA calculator S&P 500 assumptions

When people search for a UTMA calculator s&p 500 they usually want to use the long-run S&P 500 average as the return assumption. The S&P 500's nominal total return has averaged about 10% per year since 1926, and about 7% after inflation. Use 10% in this calculator for nominal dollars. Use 7% if you want the projected balance expressed in today's purchasing power. Actual year-to-year results are volatile, so treat the output as a median long-run projection rather than a guarantee.

## The kiddie tax

Unearned income in a UTMA account (interest, dividends, realized gains) is subject to the **kiddie tax** rules through age 18 (or 24 if the child is a full-time student). For 2024, the first $1,300 is tax-free, the next $1,300 is taxed at the child's 10% rate, and anything above $2,600 is taxed at the parent's marginal rate. This calculator estimates that annual tax at a 24% parent bracket. High-income families may lose more to taxes than they would in a 529 plan, which is a key tradeoff when choosing between the two.

## When a UTMA is the right choice

UTMA accounts are flexible: the money can fund college, a car, a wedding, a down payment, or a business. 529 plans are restricted to education expenses without penalty. UTMAs have no contribution limits beyond the federal gift tax exclusion ($18,000 per donor per beneficiary in 2024). The downside is that the beneficiary gains unrestricted control at the age of majority and the account counts more heavily against financial aid than a 529.

## Frequently Asked Questions

**Q: How does this UTMA calculator project growth?**

A: The calculator uses monthly compound interest. Starting balance grows at (1 + r/12)^(12 x years), and each monthly contribution grows via the future value of annuity formula. For an $5,000 starting balance plus $200/month at 10% annual return over 16 years, the projected balance is about $119,000. Adjust the annual return input to match your risk tolerance.

**Q: Why do people search for a utma calculator s&p 500 specifically?**

A: Most UTMA accounts are invested in broad-market index funds that track the S&P 500. The historical S&P 500 total return is roughly 10% nominal and 7% real (inflation-adjusted). Using those numbers as the expected annual return gives a realistic long-horizon projection. This calculator defaults to 10%, which matches the nominal S&P 500 long-run average.

**Q: What is the kiddie tax and how does it affect a UTMA?**

A: Unearned income (interest, dividends, realized gains) in a UTMA is taxed under kiddie tax rules. For 2024, the first $1,300 is tax-free, the next $1,300 is taxed at the child's 10% rate, and anything above $2,600 is taxed at the parent's marginal rate. A UTMA generating $3,000 of unearned income in a year with a parent in the 24% bracket would owe roughly $226 in kiddie tax. Large UTMAs with high turnover can generate significant annual tax drag.

**Q: UTMA vs 529 plan: which is better?**

A: A 529 plan offers tax-free growth and withdrawals for qualified education expenses, with no kiddie tax drag. A UTMA offers total flexibility of use, but its earnings are taxed annually under kiddie tax rules and count more heavily against financial aid. Use a 529 if you are confident the beneficiary will pursue education. Use a UTMA if you want flexibility for non-education uses like a first home or business seed capital.

**Q: At what age does the beneficiary take control?**

A: The age of majority varies by state. California transfers at 18. New York, Texas, and Florida transfer at 21. A handful of states allow custodians to extend to 25. This calculator defaults to 21 but lets you set the actual age of majority for your state. Once the handoff happens the beneficiary has full legal control and can use the money for anything.

**Q: Is there a contribution limit to a UTMA?**

A: No formal annual contribution limit, but gifts above the federal gift tax exclusion ($18,000 per donor per beneficiary in 2024, $36,000 for married couples splitting gifts) require a gift tax return. Most families stay under the exclusion to keep paperwork simple. Lifetime gift tax exemption is high enough that ordinary UTMA contributions rarely trigger actual tax.

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Source: https://vastcalc.com/calculators/finance/utma
Category: Finance
Last updated: 2026-04-08