California SB 343 and the New Child Support Formula: What San Diego Parents Need to Know

June 6, 2026

California changed the way it calculates child support for the first time in more than thirty years. Senate Bill 343 took effect on September 1, 2024, and it overhauled the statewide guideline that courts use in every child support case. It is the first major revision since 1992.

If you pay or receive child support in San Diego, the new rules can affect how your amount is calculated. This piece explains what SB 343 changed, who is most affected, and what it means for an existing order. Because the formula is detailed and fact-specific, it is worth reviewing your situation with a San Diego family law attorney.

What SB 343 Changed

SB 343 updated the statewide child support formula in California Family Code section 4055, the equation every court uses to set support.

At its core, child support in California still follows one principle:

“A parent’s first and principal obligation is to support his or her minor children according to the parent’s circumstances and station in life.” — Cal. Fam. Code §4053(a)

SB 343 did not change that goal. It changed the math used to reach it. The law adjusted a key part of the formula. That part is often called the K-factor. It determines how much of a parent’s income is allocated to support.

The update recalibrates the calculation for both lower-income and higher-income parents. The aim is to better reflect what families actually earn and spend.

The New Low-Income Adjustment

SB 343 also changed how California handles child support for lower-income parents. In the past, low-income adjustments were more discretionary. Under the new law, qualifying parents are entitled to the adjustment if they meet the requirements.

The threshold is now tied to full-time earnings at minimum wage. It is calculated on a 40-hour workweek over a full year, then converted to a monthly figure. The purpose is to make sure child support obligations take into account a parent’s limited income and basic living expenses.

For parents earning close to minimum wage, the adjustment can have a noticeable effect on the final support amount.

New Add-On Expenses and How They Are Shared

SB 343 also expanded the extra costs, known as add-ons, that parents share in addition to the base support amount.

The add-on categories now commonly include:

Child care needed for work or education.
Uninsured or unreimbursed medical costs.
Reasonable extracurricular activities.
Special-needs expenses.
Travel costs for visitation.

These add-ons are divided between the parents in one of two ways. They can be split equally, fifty-fifty, or in proportion to each parent’s income. The income-proportional option ties the share of these costs to each parent’s income. That choice can matter a great deal when the two incomes are far apart. The right method depends on the family’s circumstances.

How the Formula Treats Higher and Lower Earners

The updated formula adjusts support based on a parent’s income level. For lower-income parents, the revised percentages and the low-income adjustment can reduce the risk that an order becomes unmanageable. For higher-income parents, support calculations are designed to reflect income more closely than under the old formula.

Income is only part of the calculation, though. Parenting time, tax filing status, and other factors still play a role. That is why two families with similar incomes can end up with different support amounts.

SB 343 Means for San Diego Parents

What SB 343 Means for San Diego Parents

SB 343 does not automatically rewrite the support order you already have. Existing orders stay in place until a court changes them. Maybe you believe the new formula would meaningfully change your amount. If so, the path is to request a modification.

A parent can ask the court to recalculate support under the current guideline when there is a basis to do so. A modification can help one parent and not the other.

The outcome depends on your specific numbers. That is why running them carefully before filing matters.

California Child Support: Before and After SB 343

Detail	Before SB 343	After SB 343
Last major guideline change	1992	September 1, 2024
Low-income adjustment	Discretionary	Entitlement, minimum-wage threshold
Formula (K-factor)	Older calibration	Updated calibration
Add-on sharing	Limited	50/50 or income-proportional
Governing statute	Fam. Code §4055	Amended §4055
Effect on existing orders	N/A	Not automatic; modification needed

FAQs

When did California’s new child support formula take effect?

SB 343 took effect on September 1, 2024. It is the first major revision to California’s statewide child support guideline since 1992. The new formula now applies to child support calculations across the state, including in San Diego.

Does SB 343 lower or raise child support?

It depends on the specific case. The updated formula and low-income adjustment can reduce orders for lower-income parents, while recalibrating contributions for higher earners. Because the calculation has many inputs, the only way to know the effect is to run your actual numbers.

What is the new low-income adjustment?

It is a built-in reduction for parents who earn at or near minimum wage. SB 343 made it an entitlement for qualifying parents and tied the threshold to full-time minimum-wage earnings. The aim is to prevent a support order from pushing a low-income parent below the poverty line.

What expenses count as add-ons now?

Add-ons commonly include work-related child care, uninsured medical costs, extracurricular activities, special-needs expenses, and travel for visitation. These are paid in addition to base support and are shared either equally or in proportion to each parent’s income.

Will my existing child support order be automatically updated?

No. SB 343 does not recalculate existing orders on its own. Your current order remains in effect until a court modifies it. If the new formula would change your amount, you can ask the court for a modification.

Should I request a modification under the new formula?

That depends on your numbers. A modification can help one parent but not the other, so it is worth calculating the likely result first. A family law attorney can run the new formula for your situation before you decide whether to file.

Conclusion

SB 343 is the most significant change to California child support in a generation. It updates the core formula, strengthens protection for low-income parents, and broadens the add-on expenses parents share. For San Diego families, the practical question is whether the new guideline changes your number, and whether existing orders can be changed only through a modification.

If you want to understand how SB 343 affects your support order, the attorneys at The Law Offices of Steven M. Bishop, including a Certified Family Law Specialist certified by the California Board of Legal Specialization, can run the new formula for your situation. Reach out for a consultation to review your options.