California Child Support Policy 2024-2026

The K-factor is a complex variable in California's guideline formula (CS = K × HN × H%) that adjusts support based on combined parental income and custody timeshare. It accounts for the economic reality of maintaining two households for children. The factor increases with higher-earning parent's custody time, recognizing dual-household costs. Under SB 343, the K-factor formula was updated September 1, 2024, with new income bands and multipliers to better reflect current cost of living.

SB 343, effective September 2024 and fully implemented January 2026, fundamentally restructures California's child support guideline. Key changes include: updated income bands for K-factor calculation, refined definition of net disposable income, modified treatment of mandatory retirement contributions, and new rules for allocating add-on costs like childcare and medical expenses. The law aims to better reflect current economic conditions and ensure children receive adequate support in two-household arrangements.

California law requires three categories of expenses to be added to base guideline support and prorated between parents: (1) reasonable work-related childcare costs necessary for employment or education, (2) the marginal cost of health insurance premiums specifically for the children, and (3) uninsured or unreimbursed medical and dental expenses exceeding $250 per year. These add-ons are calculated separately from the guideline formula and allocated proportionally to each parent's share of combined net disposable income.

While California's guideline amount is presumptively correct, courts may deviate if applying it would be unjust or inappropriate under Family Code § 4057. Common grounds for deviation include: extremely high or low parental income, children with special needs requiring extraordinary expenses, significant travel costs for visitation, or when a parent has custody less than substantial periods. Any deviation must be supported by specific findings and stated reasons to ensure children's needs remain the primary consideration.

Timeshare percentage (H%) is calculated by dividing total annual hours a parent has physical custody by 8,760 (hours per year). A typical alternating weekend schedule equals approximately 14-20% timeshare, while 50/50 custody equals 50%. This percentage is crucial because it directly affects the K-factor calculation—higher-earning parent's increased custody time reduces support obligation, recognizing they incur more direct child-rearing costs during their parenting time.

California Family Code § 4058 defines income broadly as "income from whatever source derived." Includable sources: wages, salaries, bonuses, commissions, self-employment income (gross receipts minus necessary business expenses), rental income, investment returns, Social Security retirement benefits, unemployment benefits, spousal support from another relationship, and imputed value of employer-provided benefits like company cars. Excluded: SSI, child support received, need-based public assistance, and student loan principal.