The kiddie tax under IRC §1(g) taxes a child's net unearned income above a threshold at the parent's marginal rate rather than the child's lower rate. Congress enacted the kiddie tax to prevent high-bracket parents from shifting investment income to their children to take advantage of the child's zero or 10% tax rate. The rules apply more broadly than many families realize - they cover not just young children but full-time students up to age 23, and they apply regardless of whether the child files a joint return.
Kiddie tax threshold: $2,500 of net unearned income for 2026 (indexed annually). The first $1,250 is covered by the child's standard deduction; the next $1,250 is taxed at the child's rate; anything above $2,500 is taxed at the parent's rate.
Who is subject: A child who (1) has net unearned income above the threshold, (2) has at least one living parent at year-end, (3) does not file a joint return, and (4) is under age 19, OR is a full-time student under age 24 who does not have earned income exceeding half of their support.
The child's unearned income is divided into three tiers for 2026:
Tier 1 - $0 to $1,250: Sheltered by the child's standard deduction (allocated to unearned income first). No tax.
Tier 2 - $1,251 to $2,500: Taxed at the child's own marginal rate. If the child has little or no other income, this is the 10% bracket.
Tier 3 - Above $2,500 (Net Unearned Income): Taxed at the parent's marginal rate - whatever rate the parent would pay on an additional dollar of income. If the parent is in the 37% bracket, the child's investment income above $2,500 is also taxed at 37%.
Unearned income includes: interest, dividends (including qualified dividends), capital gains distributions, taxable scholarships not used for tuition, and trust income that is not compensation for services. It does not include wages, salaries, self-employment income, or amounts received under a retirement plan. Qualified dividends and long-term capital gains retain their preferential character even when subject to the kiddie tax - they are still taxed at the preferential rates (0%/15%/20%) but at the parent's income level bracket rather than the child's.
A full-time student (enrolled for at least five calendar months during the year) who is under age 24 is subject to the kiddie tax unless the student's earned income exceeds half of their support. Support includes tuition, room, board, clothing, transportation - the full cost of supporting the student for the year. For most college students supported primarily by parents, the earned income (summer job wages) does not exceed half of total support, so the kiddie tax applies. A student who becomes financially self-supporting - earning wages that exceed half of their total support costs - escapes the kiddie tax regardless of age under 24.
The kiddie tax is computed on Form 8615 (Tax for Certain Children Who Have Unearned Income), which is attached to the child's Form 1040. The form requires the parent's taxable income and filing status. The parent's return does not need to be completed first - the parent's tax information can be estimated and Form 8615 amended if the parent's return changes. Alternatively, the parent may elect to include the child's unearned income on the parent's own return using Form 8814, avoiding a separate child return - but only if the child's income consists solely of interest and dividends under $11,500 and no estimated tax payments were made in the child's name.