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California child support calculator
See exactly what you'd owe — or be owed. The same formula judges use.
Family Code § 4055 guideline formula with 2026 federal and California tax tables. Free, no account required.
Currently California only. Other states coming soon.
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Plain English, no legal jargon
Party 1 — Gross Monthly Income
Guided calculator
RecommendedNew to child support? Start here. We walk you through each input one step at a time with plain English explanations and tax return references.
8 steps · About 5 minutes
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Know your numbers? Enter everything on one page. Same FC 4055 formula, all inputs visible at once.
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Open advanced →What this calculator does
This calculator implements the California Family Code § 4055 guideline formula — the same formula judges use to determine child support. It calculates net monthly disposable income for each parent using 2026 federal and California tax tables, applies the K-factor formula based on combined income and timeshare percentage, and outputs a guideline child support amount.
If the paying parent's net income falls below the minimum wage threshold ($2,929/month), a Low-Income Adjustment flag is applied per FC § 4055(b)(7).
Childcare and uninsured medical expenses (SB 343 add-ons) are calculated separately and allocated proportionally by income.
FC § 4055 Formula
This calculator provides an estimate only. Results are based on California Family Code Section 4055 and 2026 tax tables. The actual child support order is determined by a judge or commissioner and may differ from this estimate. This tool does not constitute legal advice. Consult a licensed California family law attorney.