How much regular federal tax does one child's investment income create?
Estimate the regular federal tax on a single child's wages and investment income under the supported Form 8615 rules. Check age, student status, earned-income support and living-parent conditions, preserve ordinary income versus qualified dividends and net long-term gains, and calculate the incremental parent tax rather than multiplying all investment income by a flat parent rate.
kiddie tax calculator
Quick answer
For supported eligible children, calculate incremental parent tax on net unearned income with its original income character, add child-remainder tax, and compare with the child's own-tax floor.
Also answers
- Form 8615 calculator
- child investment income tax
- kiddie tax capital gains
- student support kiddie tax
Good fit when
- Single-child interest/dividend tax scenarios
- Testing age and support boundaries
- Comparing ordinary versus preferential child income
Have ready
- IRS age, student status, earned income, support and dependency
- Ordinary investment income, qualified dividends and net long-term gains
- Correct parent status, taxable income and preferential income
- Single-child and supported-income scope confirmations
Result you get
Eligibility, child deduction and taxable income, Form 8615 parent allocation, parent-base and combined tax, child remainder and additional kiddie tax.
How this calculation works
- Use the IRS year-end age convention. The supported eligibility test covers children under 18, age 18 with earned income not exceeding half of support, and full-time students ages 19-23 under the same earned-income test, with a living parent and a single child return.
- Apply the dependent standard deduction when the child can be claimed; otherwise apply the regular single deduction. Determine taxable income and net unearned income using the verified $2,700 threshold for 2025 and 2026.
- Follow the standard-deduction Line 5 worksheet allocations for preferential income. Compute parent tax with the child's net unearned income and allocated gain/dividends, subtract parent-base tax, and add tax on the child's remaining taxable income. Keep at least the child's own-tax amount.
- Worked 2026 ordinary-income example: dependent age 16, no wages, $10,000 interest and joint parent taxable income of $100,000. Child deduction is $1,350 and net unearned income is $7,300. Parent increment is $1,526 across two brackets, child remainder tax is $135, and total regular child tax is $1,661 versus $865 without Form 8615.
Common mistakes and caveats
- Other children with net unearned income are blocked because Form 8615 requires a combined parent calculation and allocation. The selected parent must be the proper Form 8615 parent, not automatically the parent in the lower bracket.
- This version supports the child's ordinary standard deduction and single filing only. Itemizing, child blindness additions, taxable scholarships, capital losses, investment-interest elections, collectibles/1250 gains, Schedule J and foreign exclusions are blocked.
- Parent preferential income must not exceed parent taxable income in this supported model. Inputs are taxable ordinary unearned income and net positive gains; this is not a stock-basis, loss-netting, parental-election Form 8814 or withholding calculator.
- 2027 indexed federal amounts that have not been published use clearly labeled provisional 2026 baselines, not invented inflation forecasts. Tax is computed using continuous ordinary/capital-gain schedules; final Form 8615 can differ from IRS tax-table rounding. NIIT and other special taxes are excluded.
FAQ
Is all investment income taxed at the parent's marginal rate?
No. Form 8615 uses net unearned income after the threshold, the parent's actual tax base, the child's remaining taxable income and an own-tax floor. Income can cross parent brackets; qualified dividends and net long-term gains generally retain their preferential character.
Can the rule apply at age 18 or to a college student?
Yes. Age 18 and full-time students ages 19 through 23 can qualify when earned income is not more than half of support. Scholarship amounts are excluded from a full-time student's support calculation. Merely using savings to pay expenses does not turn investment income into earned income.
What happens exactly at half of support?
For the relevant older-child tests, earned income must be more than half of support to avoid the age/support condition. Equality still satisfies that condition. Other conditions, including unearned income, a living parent and a filing requirement, must also hold.
Which parent's taxable income should I enter?
Married parents filing jointly use the joint return. Married separate parents generally use the greater taxable-income return. Custodial-parent, remarriage and parents-not-living-together rules can alter the selection; confirm the applicable Form 8615 rule before using the parent input.
Why is another child a blocking condition?
Other children's net unearned income affects the parent's combined tax and the share allocated to this child. Computing each child separately without that combined calculation can produce the wrong tax. This first version deliberately supports only a single-child calculation.
Does the tool include taxable scholarship income?
No. Scholarships have special earned/unearned definitions for deduction and kiddie-tax purposes. This engine blocks them rather than treating every grant as ordinary interest or wages. It also does not model itemized deductions, foreign exclusions or special capital-gain categories.
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