California Child Support Calculator
Calculate child support using California's official guideline formula
Based on Family Code Section 4055
Based on Family Code Section 4055
How California Calculates Child Support
The California Guideline Formula
California uses a statutory formula defined in Family Code Section 4055. The formula is:
CS = K[HN - (H%)(TN)]
Where:
- CS = Child Support amount
- K = Amount of both parents' income to be allocated for child support
- HN = High earner's net monthly disposable income
- H% = High earner's approximate time-share with children
- TN = Total net monthly disposable income of both parents
This complex formula ensures that support is based on actual income and accounts for how much time each parent spends with the children.
California-Specific Rules
- Uses a complex algebraic formula (the "Dissomaster" or similar software is commonly used)
- California is one of the few states that considers time-share percentage so heavily
- Add-on expenses (childcare, uninsured medical, education) are split separately
- Courts can deviate from guidelines only under specific circumstances
- Support continues until age 18 or 19 if child is still in high school
Factors That Affect California Child Support
Both Parents' Net Disposable Income
California uses net monthly disposable income, which includes wages, bonuses, commissions, rental income, and other sources after taxes and mandatory deductions.
Time-Share Percentage
The percentage of time each parent spends with the child directly impacts the support amount. More time with the child typically means lower support obligation.
Number of Children
Support increases with additional children, but not proportionally. The guideline percentage increases at a declining rate for each additional child.
Tax Filing Status
How each parent files taxes affects net disposable income calculations and ultimately the support amount.
Health Insurance Costs
Costs for children's health insurance are factored into the calculation and may be added to base support.
Mandatory Payroll Deductions
Union dues, retirement contributions, and other mandatory deductions reduce net disposable income.
Add-On Expenses in California
Mandatory Add-Ons
- Childcare costs for employment or education
- Uninsured healthcare expenses for the children
- Health insurance premiums for children's coverage
These expenses are typically split in proportion to each parent's income, separate from the base child support amount.
Discretionary Add-Ons
- Private school tuition (if mutually agreed or court-ordered)
- Educational tutoring for special needs
- Extracurricular activities and travel costs
- Special needs expenses beyond basic support
Courts may order these expenses to be shared if it's in the child's best interest and parents can afford it.
Calculate Your California Child Support
Use our free calculator to estimate child support based on California guidelines. Splitifi can also help you track payments, document expenses, and plan custody schedules.