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California Family Law

California SB 343 Explained: Complete Guide to Child Support Changes

Understanding how California's transition to the income shares model affects child support calculations, K-factor adjustments, and your case strategy.

Published January 15, 2024
8 min read

Critical Update: SB 343 in Effect

California switched from the DissoMaster formula to an income shares model effective January 1, 2024. All new cases and modifications must use the new calculation method.

What Actually Changed Under SB 343?

Before SB 343

• DissoMaster/XSpouse software formulas

• County-specific variations

• Inconsistent application

• Limited transparency

After SB 343

• Standardized income shares model

• State-wide consistency

• Transparent calculation tables

• K-factor for shared custody

The most significant change is the move to an income shares model that considers both parents' income and the estimated cost of raising children. This replaces county-specific formulas that varied significantly across California.

How the New Income Shares Model Works

1

Calculate Combined Gross Income

Add both parents' gross monthly income from all sources. This includes salary, bonuses, rental income, and other regular income streams.

2

Apply Income Shares Table

Use the official table to find the basic child support obligation based on combined income and number of children. The table reflects economic data on child-rearing costs.

3

Calculate K-Factor Adjustment

If the non-custodial parent has significant parenting time, apply the K-factor to account for expenses in both households. This prevents double-counting of certain costs.

4

Add Additional Expenses

Include health insurance premiums, work-related childcare, and other allowable add-ons as specified in the statute.

Understanding the K-Factor

K-Factor Formula
K = (H × 0.025) - 1
Where H = overnight visits per year for non-custodial parent

The K-factor reduces support when the non-custodial parent has substantial parenting time, recognizing that they incur direct costs during their parenting time.

146+ nights
Shared physical custody
Significant K-factor
73-145 nights
Substantial parenting time
Moderate K-factor
< 73 nights
Limited parenting time
Minimal K-factor

Practical Impact on Your Case

Benefits of the New System

Consistency: Same calculation method statewide

Transparency: Clear formulas and tables

Predictability: More reliable estimates

Fairness: Based on economic research

Transition Considerations

• Existing orders remain valid until modified

• New cases must use SB 343 calculations

• Modification requests should compare old vs new amounts

• Software vendors updated their programs by 2024

Try Our California SB 343 Calculator

Get accurate child support estimates using the new income shares model and K-factor calculations.

Calculate California Child Support

Key Takeaways

California's SB 343 represents the most significant change to child support calculations in decades. The income shares model provides greater consistency and transparency than the previous county-specific formulas.

Understanding the K-factor is crucial for cases involving shared custody, as it can significantly impact support amounts. The new system better reflects the actual costs of raising children in both households.

For pending cases or modifications, consult with a family law attorney to understand how SB 343 affects your specific situation and whether it's advantageous to seek a modification.