Free California Child Support Calculator

Free, independent estimator for informational and educational purposes

SupportSplit is a free California child support estimator that uses the state guideline formula with real 2026 federal and California tax brackets. Enter your income and your co-parent's income, set your custody schedule, and see what guideline support looks like for your situation.

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How it works

California uses a statewide formula, Family Code §4055, to calculate guideline child support. The formula takes each parent's income (after taxes and deductions), the percentage of time the child spends with each parent, and the number of children. SupportSplit computes this with real marginal tax brackets, not flat-rate estimates.

What we calculate

2026 federal income tax (7 brackets, 10% to 37%)
2026 California income tax (10 brackets, 1% to 13.3%)
Social Security, Medicare, and California SDI
Standard vs. itemized deductions (auto-selected)
SALT cap with OBBBA phasedown
Pre-tax deductions (401(k), IRA, HSA)
Post-tax deductions (health insurance, union dues, hardship)
K-factor income bands per SB 343
Child multipliers for 1 through 5 children
Low-income adjustment
Add-on expense allocation

Free and private

All calculations run in your browser. Nothing is sent to a server. No signup required, no data stored.