What Is the Kiddie Tax and When Does It Apply to a Child's Income?
A custodial account opened years ago for a child has grown, dividends and gains are showing up on paper, and now tax season raises a question nobody expected to have to think about this early: does a kid actually owe taxes, and at what rate?
The short answer
The kiddie tax is a federal rule that applies a parent’s marginal tax rate, rather than the child’s typically lower rate, to a child’s unearned income above a certain threshold. It generally applies to investment-type income such as interest, dividends, and capital gains, not wages from a job, and it kicks in for dependent children under a specific age cutoff who meet the income rules. The point of the rule is to prevent parents from shifting large amounts of investment income into a child’s name purely to have it taxed at a lower rate.
What counts as unearned income
Unearned income covers things like interest from savings, dividends from stocks, and capital gains from selling investments, typically inside a custodial account set up in the child’s name. Wages a teenager earns from an actual job are treated as earned income and aren’t subject to the kiddie tax, which only concerns income the child didn’t work for. A child with a mix of both types of income has each treated separately for this purpose, so a summer job paycheck doesn’t get pulled into the same calculation as dividends from a custodial brokerage account.
Who the rule applies to
The kiddie tax generally applies to dependent children under a set age threshold, with an extension for full-time students up to a somewhat higher age, though the exact age cutoffs and dollar thresholds are set by tax law and change periodically, so checking current figures each filing year matters. A small amount of a child’s unearned income is typically exempt, a further slice is taxed at the child’s own rate, and only the amount above both thresholds is taxed at the parent’s rate. This tiered structure means many children with modest custodial account balances never actually trigger the higher-rate portion of the rule at all.
How the tax actually gets filed
Depending on the amounts involved, a child’s unearned income can sometimes be reported directly on the parent’s own tax return using a specific election, or it can be reported on a separate return filed for the child, with the kiddie tax calculation applied there. Each approach has different implications, including how the income might interact with other parts of a parent’s return, which is why this is an area where the mechanics can genuinely differ from one household’s tax situation to the next. The rules around a custodial account and when a child actually gains control of it are separate from the kiddie tax itself, but the two often come up together since custodial accounts are a common source of the unearned income the rule targets.
Why this trips people up
Grandparents or other relatives sometimes contribute to a child’s account without realizing the growth could eventually be taxed at a parent’s higher rate rather than a low or nonexistent child rate. The rule can also catch families off guard when an inherited account, like one that came with an inherited IRA’s own separate rules, starts generating income in a child’s name without anyone tracking the cumulative unearned income across the year. Because thresholds and age rules are set by statute and adjusted periodically, an amount that was too small to matter one year can cross the line in another, especially as an account grows.
Final thoughts
The kiddie tax exists to stop large amounts of investment income from being taxed at a child’s low rate simply because the account is titled in the child’s name, and it only reaches unearned income above set thresholds. Understanding which type of income a child has, how much of it is unearned, and how current thresholds apply is what determines whether this rule ends up mattering for a given account at all.