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

By Recording Law Editorial TeamPublished June 20, 20267 min read

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.

Key Takeaways

1California's SB 343 (Chapter 213, Statutes of 2023) became operative on September 1, 2024, the first major rewrite of the state's child support formula since 1992.
2The law amends Family Code Sections 4055, 4057, 4058, 4061, 4062, and 4063 and adds Sections 3635 and 17432.5, among other changes.
3The K-factor income bands in Family Code 4055 were rewritten, changing how a parent's net disposable income is allocated to support.
4The low-income adjustment is now indexed to the state minimum wage rather than a fixed dollar figure, raising the threshold that triggers a rebuttable presumption of relief.
5Add-on costs for child care and uninsured health care are now allocated in proportion to each parent's net income by default, not split 50/50.
6California Child Support Services made the new guideline the default in its official calculator as of September 1, 2024.

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 parent seen from behind at a kitchen table with a plain grey laptop, mug and closed folder

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.

gavel resting next to reading glasses on a dark surface

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.

a father kneeling on a porch step tying his toddler's shoe, seen from the side

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.

More California Laws

Frequently Asked Questions

When did California's SB 343 child support changes take effect?

SB 343 was chaptered as Chapter 213, Statutes of 2023, and its guideline changes became operative on September 1, 2024. Certain provisions affecting local child support agencies carry a later operative date of January 1, 2026.

What is the main thing SB 343 changed?

It rewrote the K-factor income bands inside the statewide guideline formula in Family Code Section 4055 and re-indexed the low-income adjustment to the state minimum wage. It also changed how add-on costs like child care and uninsured health care are allocated, using each parent's share of net income by default.

Does SB 343 change my existing child support order automatically?

No. The new formula governs new orders and modifications going forward. An existing order generally does not change on its own, and modifying it typically requires returning to court or the local agency and showing a change in circumstances.

How does the new low-income adjustment threshold work?

Family Code Section 4055 now sets the threshold using 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. When a paying parent's net income falls below that figure, there is a rebuttable presumption of a low-income adjustment.

Where can I find the official California child support calculator?

California Child Support Services hosts the official guideline calculator at childsupport.ca.gov, and it has used the SB 343 guideline as the default since September 1, 2024. The Judicial Branch of California also maintains guideline support calculators used in the AB 1058 program.

Was this really the first update in decades?

The income bands used to compute the K-factor had not been substantively updated in roughly 32 years, which is why officials and practitioners have described SB 343 as the first major revision to the state's child support guideline since 1992.

The Law Behind This Article

This article rests on the statutory provisions below, held in our own legal record and retrieved from the official source. Tap a section to read the operative text.

California Family Code

§ 4055In forcecited in 2 of our articles

(a) The statewide uniform guideline for determining child support orders is as follows: CS = K[HN - (H%)(TN)]. (b) (1) The components of the formula are as follows: (A) CS = child support amount. (B) K = amount of both parents’ income to be allocated for child support as set forth in paragraph (3). (C) HN = high earner’s net monthly disposable income. (D) H% = approximate percentage of time that the high earner has or will have primary physical responsibility for the children compared to the other parent. In cases in which parents have different time-sharing arrangements for different children, H% equals the average of the approximate percentages of time the high earner parent spends with each child. (E) TN = total net monthly disposable income of both parties. (2) To compute net disposable income, see Section 4059.

Official text (excerpt) · last checked 2026-09-03 · Read the full text in our law library · Verify at leginfo.legislature.ca.gov

Cited in 82 court opinions in our collectionLatest citing opinion in our collection: 2026

In the courts (editorial summary, independently checked):California courts treat the section 4055 formula as a calculation the court must perform. In Re Marriage of Drake held the guidelines reach a disabled adult child, with room to depart for special circumstances, and In Re Marriage of Whealon reversed an order where the court estimated the guideline amount instead of recomputing it.

Opinions citing this section in our collection:

In Re Marriage of Drake (California Court of Appeal 1997, 53 Cal. App. 4th 1139)✓A millionaire father resisted increased support for his adult son with chronic schizophrenia; on an issue of first impression the court held the Family Code section 4055 guideline formula reaches adult children, and affirmed support of about $3,670 a month plus add-ons.
In Re Marriage of Whealon (California Court of Appeal 1997, 53 Cal. App. 4th 132)✓After the mother moved to Syracuse with their son, the trial court used a 20 percent time-share factor when 28 percent was correct, then estimated the difference; the court held section 4055 requires an accurate figure and reversed those support orders.
In Re Marriage of Bardzik (California Court of Appeal 2008, 165 Cal. App. 4th 1291)“…e uniform guideline for determining child support orders." (Fam. Code, § 4055, subd. (a).) Also part of the 1984 Ag…”