When Your Child's Portfolio Works Against You: Understanding the Kiddie Tax and How to Protect Your Family's Bottom Line

Teaching children about investing is a widely praised financial habit. Parents who open custodial brokerage accounts, gift appreciated stock, or transfer income-producing assets to their minor children often do so with the best intentions — building wealth early, instilling financial literacy, and occasionally reducing the family's overall tax burden. What many of those same parents discover at tax time, however, is that the Internal Revenue Service anticipated this strategy decades ago and wrote specific rules to counteract it.

Those rules collectively form what tax professionals refer to as the kiddie tax. For families caught off guard, the consequences can be significant.

What the Kiddie Tax Actually Is

The kiddie tax originated in the Tax Reform Act of 1986, introduced specifically to prevent high-income parents from shifting investment income to children who were subject to much lower marginal rates. The mechanics are straightforward: when a child's net unearned income — think dividends, capital gains, and interest — exceeds a threshold set by the IRS each year, the excess is taxed at the parent's marginal rate rather than the child's.

For the 2024 tax year, the first $1,300 of a child's unearned income is tax-free. The next $1,300 is taxed at the child's own rate, which is typically quite low. Any amount beyond $2,600 is where the kiddie tax takes hold, applying the parent's top marginal rate to that remaining income. In a household where the parents are in the 32 or 37 percent bracket, the difference between the child's rate and the parents' rate can translate into thousands of dollars in additional tax.

Who Is Caught in the Net

One of the most common misconceptions is that the kiddie tax only applies to young children. In reality, the provision reaches much further. The rule currently applies to:

• Children under age 18 at the end of the tax year
• Children ages 18 who do not have earned income exceeding half of their own support
• Full-time students between ages 19 and 23 who similarly do not earn more than half of their support through wages or self-employment

This last category surprises many families. A college junior with a modest internship income but a well-funded custodial account generating $8,000 in dividends could easily find that most of that investment income is taxed at mom and dad's rate — not their own.

A Concrete Example of How the Math Plays Out

Consider a family where the parents file jointly and fall into the 24 percent federal bracket. Their 20-year-old daughter is a full-time student who earned $4,000 from a part-time job — well below half of her annual support. Her custodial account, funded with appreciated stock transferred years earlier, generates $9,000 in qualified dividends.

Here is how the kiddie tax applies:

• First $1,300: exempt from federal tax
• Next $1,300: taxed at the daughter's rate (likely 0 percent on qualified dividends given her income level)
• Remaining $6,400: taxed at the parents' 24 percent marginal rate

The family owes roughly $1,536 in additional federal tax on that final tranche of income — money they would not have owed had the daughter's earned income been higher, or had the account been structured differently. Multiply this across several years of college and the cumulative impact becomes material.

Common Mistakes Families Make

Beyond failing to recognize the kiddie tax exists, several planning errors repeatedly surface in tax practice.

Transferring highly appreciated assets without considering the holding period. Gifting stock that is likely to generate a large capital gain shortly after transfer can accelerate income into a year when the kiddie tax is still in effect.

Ignoring the interaction with the net investment income tax. High-income parents subject to the 3.8 percent net investment income surtax may find that their child's unearned income compounds this exposure.

Assuming custodial accounts are always tax-efficient. Many parents open UGMA or UTMA accounts believing they are creating a tax shelter. Without careful management of the income those accounts generate, the shelter can quickly become a liability.

Overlooking Form 8615. This is the IRS form used to calculate the kiddie tax. Failing to file it when required can trigger penalties and interest — and the IRS has become increasingly sophisticated at matching 1099 data to returns where the form is absent.

Planning Strategies That Can Reduce the Damage

The kiddie tax is not inevitable. With thoughtful planning, families can significantly reduce or even eliminate its impact.

Choose growth-oriented investments over income-producing ones. Assets that appreciate in value rather than paying regular dividends or interest generate no taxable income until sold. Index funds with low turnover and growth-focused equities are natural fits for custodial accounts subject to kiddie tax risk.

Time asset sales strategically. If a child is approaching age 24 or is expected to have substantial earned income in a future year, delaying the realization of gains can shift the tax liability to a period when the kiddie tax no longer applies — and when the child's own rate governs the transaction.

Consider 529 college savings plans instead of custodial accounts. Funds invested in a 529 plan grow tax-deferred and are distributed tax-free when used for qualified education expenses. There is no kiddie tax exposure within a 529, making it a structurally cleaner vehicle for education savings.

Evaluate Roth IRA contributions for working teens. A child with earned income can contribute to a Roth IRA up to the amount of that earned income or the annual contribution limit, whichever is lower. Investment growth inside the Roth is not subject to the kiddie tax and compounds tax-free for decades.

Manage the income threshold deliberately. In years when a child's unearned income is likely to approach the kiddie tax threshold, consider tax-loss harvesting within the account to offset gains, or deferring dividend-heavy fund distributions through careful fund selection.

When to Bring in a Professional

The kiddie tax sits at the intersection of family financial planning, investment management, and federal tax law. That convergence makes it genuinely complex — and the cost of misunderstanding it can accumulate quietly over years before appearing on a tax return. Families with custodial accounts, appreciated assets they intend to transfer, or college-age children with investment income should review their situation annually.

At RyanTax Pro, we work with families to map out the full tax picture before decisions are made, not after. Identifying kiddie tax exposure early — before a dividend-heavy fund is purchased or a block of appreciated stock is transferred — creates options. Discovering it in April, after the tax year has closed, leaves very few.

The rules governing children's investment income are detailed, but they are not impossible to navigate. With the right information and a clear view of your family's financial structure, the kiddie tax becomes a manageable consideration rather than an unexpected bill.