California Overhauls Child Support Math for the First Time Since 1992 Under SB 343

California has rewritten the core formula it uses to set child support for the first time in more than three decades. Senate Bill 343, signed in 2023 and operative since September 1, 2024, revises the statewide uniform guideline in Family Code Section 4055 and a cluster of surrounding statutes. The change touches nearly every new and modified order in the state, especially for lower-income parents.

Information last verified on June 20, 2026.

What Changed

The statewide guideline formula keeps its familiar shape. Family Code Section 4055 still expresses child support as CS = K[HN - (H%)(TN)], where CS is the support amount, K is the share of combined income allocated to support, HN is the high earner's net monthly disposable income, H% is the high earner's approximate share of physical responsibility for the child, and TN is the total net monthly disposable income of both parents. The text of Section 4055 confirms it is operative September 1, 2024, as amended by Stats. 2023, Ch. 213, Sec. 3.

What changed is the engine inside that formula. SB 343 replaced the table used to compute K. Under the in-force statute, K is now set across income bands that run from 0.165 plus TN over 82,857 at the lowest range up to 0.12 plus 1,200 over TN for combined net income above 15,000 dollars per month. The income bands had not been refreshed in roughly 32 years, so the practical effect is a formula that better tracks current earnings and living costs.

The low-income adjustment was also reworked. Family Code Section 4055 now ties the threshold for a rebuttable presumption of a low-income adjustment to full-time earnings at the state minimum wage under Labor Code Section 1182.12, calculated as the hourly minimum wage times 40 hours per week times 52 weeks per year, divided by 12. That replaces the older fixed-dollar trigger and lets the threshold rise automatically as the minimum wage rises. The arithmetic is straightforward: at a 16.00 dollar hourly minimum wage the threshold works out to about 2,773 dollars per month, and at the 16.90 dollar minimum wage in effect in early 2026 it is about 2,929 dollars per month, the figure the Judicial Branch lists in its current guideline materials.

The Statute Behind the Headline

The authority for all of this is the bill itself. SB 343, authored by Senator Skinner, was chaptered by the Secretary of State on September 22, 2023, as Chapter 213, Statutes of 2023. The official title states that the act amends, repeals, and adds Sections 4055, 4057, 4058, 4061, 4062, 4063, 17400, 17404.1, 17430, and 17432; adds Sections 3635 and 17432.5; and repeals the chapter beginning at Section 3620 of the Family Code, all relating to child support.

A few of those provisions deserve attention. Section 4058 now directs courts on when to use a parent's earning capacity rather than actual income, and it lists factors such as employment history, job skills, education, age, health, and employment barriers. The statute also provides that incarceration or involuntary institutionalization shall not be treated as voluntary unemployment, a meaningful change for parents who fall behind while unable to work.

Sections 4061, 4062, and 4063 govern the mandatory add-ons that sit on top of base support. Child care related to employment and uninsured health care costs remain add-ons, but under the revised law these costs are allocated between parents in proportion to net income by default rather than divided evenly. The statute also lengthens the window for seeking reimbursement of certain costs and creates a presumption that amounts actually paid for job-related child care and health care are reasonable.

How Parents and Agencies See the Change

The shift is already baked into the tools families and courts use. The official California Guideline Child Support Calculator run by California Child Support Services switched its default to the SB 343 guideline as of September 1, 2024. The Judicial Branch of California likewise maintains guideline support calculators used in the AB 1058 child support program, which reflect the operative formula.

Because California uses an income-shares-style guideline, the size of a given change depends on the specific incomes, the parenting-time percentage, and which add-ons apply. As of mid-2026, the new formula is the law for new orders and for modifications, and parents seeking to modify an existing order generally must still show a change in circumstances before a court will recalculate support.

California is the largest of several states that revisited child support math in this window. For broader context on how the federal-state child support system fits together, see our overview of United States child support laws. Readers comparing systems across the border can review how Canada structures support under the federal tables in our guide to Canada child support laws, including province-specific pages such as Prince Edward Island child support and Yukon child support.

Analysis: Why This Matters

The Recording Law Editorial Team views SB 343 as one of the most consequential family-law updates in years precisely because it is not flashy. The formula sits underneath nearly every California support order, so a quiet change to the K-factor table and the low-income threshold reaches far more families than any single appellate ruling would.

The most important policy choice in the law is indexing the low-income adjustment to the minimum wage. A fixed-dollar threshold erodes with inflation and, over a 32-year stretch, drifts badly out of date. Tying the trigger to a moving wage figure means the protection keeps pace without waiting for the Legislature to act again. That is a structural fix, not a one-time bump.

The earning-capacity and incarceration provisions in Section 4058 also signal a federal-aligned trend toward setting orders parents can actually pay. Federal child support policy has pushed for years toward right-sized orders that reduce unpayable arrears, and California's statute moves in the same direction by limiting when courts impute income and by clarifying that time behind bars is not voluntary unemployment.

None of this is legal advice, and the precise dollar effect of the new formula varies case by case. Parents with an order entered before September 1, 2024, should understand that the new math does not rewrite their order automatically. A modification still requires going back to court or the local agency and, in most cases, showing changed circumstances. The takeaway is that the rules of the game changed quietly but broadly, and anyone establishing or modifying support in California should be working from the current guideline, not a calculator built on the pre-2024 bands.