The Kiddie Tax is the tax levied on the portion of your child's unearned income that exceeds $2,100. Children who only had earned income from a job or self-employment, don’t make enough money to be required to file, or are filing jointly with their spouses are exempt from the Kiddie Tax.
In 2017, the Kiddie Tax rate was equal to the parent’s highest marginal tax rate (the rate applied to their last dollar of income), which could be as low as 10% or as high as 39.6%.
The Tax Cuts and Jobs Act (TCJA) made substantial changes to the Kiddie Tax in 2018 through 2025. Instead of using the parent’s highest marginal rate, the Kiddie Tax is now determined by the tax brackets and rates for trusts and estates. Here’s what those work out to:
The first $2,550 (after the initial $2,100) is taxed at 10%
The next $6,600 is taxed at 24%
The next $3,350 is taxed at 35%
Anything beyond that is taxed at 37%
Remember that the Kiddie Tax only applies to unearned income in excess of $2,100. Here’s a step-by-step illustration of how a child with $15,000 of unearned income in 2018 would be taxed under the new law:
Regular tax rates apply to the first $2,100, which is exempt from the Kiddie Tax. The remaining $12,900 is subject to the Kiddie Tax.
The first $2,550 is taxed at 10%, leaving $10,350 to roll up to a higher rate.
$6,600 of the $10,350 is taxed at 24%, leaving $3,750.
$3,350 of the $3,750 is taxed at 35%, leaving $400.