California Child Support Calculator
California uses an algebraic statewide formula — CS = K[HN − (H%)(TN)] — driven by both parents' net disposable incomes and how parenting time is shared. This calculator implements the current Family Code §4055 formula as rewritten by SB 343 (operative September 2024), including the multi-child multipliers and the 2026 low-income adjustment threshold of $2,929/month.
After taxes/FICA, Fam. Code §4059
After taxes/FICA, Fam. Code §4059
Percent of time the children spend with Parent A
§4061/§4062 mandatory add-on
§4061/§4062 mandatory add-on
Estimated monthly child support
$1,644.46Parent A
Annual amount
$19,733.52Who pays
Parent A| Step | Amount |
|---|---|
| Combined net monthly disposable income (TN) | $11,000.00 |
| K-fraction (TN band $10,001–$15,000) | 0.24 |
| Multiplier (1 + H%) | 1.2 |
| K (multiplier × fraction) | 0.28 |
| HN − H% × TN | $5,800.00 |
| 1-child presumptive CS (K × (HN − H% × TN)) | $1,644.46 |
| Total monthly transfer | $1,644.46 |
This is a guideline estimate under Cal. Fam. Code §4055 (SB 343) for informational purposes only — it is not legal advice and not a substitute for the official worksheet or a family-law attorney. Courts can deviate from guideline amounts based on statutory factors, and inputs like income determination or imputed income are ultimately decided by the court.
California child support at a glance
| Model | Income shares (algebraic formula) |
| Formula | CS = K[HN − (H%)(TN)] |
| 2-child / 3-child multiplier | ×1.6 / ×2.0 |
| Low-income threshold (2026) | $2,929/month net |
| Statute | Cal. Fam. Code §4055 (SB 343) |
Net disposable income
The formula runs on each parent's net monthly disposable income per §4059: gross income minus actual income taxes (by actual filing status), FICA, mandatory union dues and retirement, health premiums, and certain hardships. Enter your net figures directly — that is exactly what the statute uses. California's official DCSS online calculator computes net from a full tax profile, but it has been decertified since December 2025 because its tax tables don't yet reflect the 2025 federal tax law changes.
Parenting time drives the result
H% is the higher earner's approximate share of time with the children — more time with the higher earner shrinks (or flips) the transfer. At exactly 50/50 time, support usually still flows from the higher earner because their income share exceeds their time share.
Low-income adjustment
If the paying parent's net disposable income is below the full-time state minimum wage equivalent — $2,929/month in 2026 ($16.90/hr × 40 hrs × 52 weeks ÷ 12) — there's a rebuttable presumption of a reduction of up to CS × (threshold − income) ÷ threshold. The threshold rises each January 1 with the minimum wage.
Frequently asked questions
What is the California child support formula?
CS = K[HN − (H%)(TN)] under Family Code §4055, as rewritten by SB 343 effective September 1, 2024. K is built from a fraction that depends on combined net income (five bands — for example, a flat 0.250 for combined net of $5,001–$10,000/month) times a parenting-time multiplier (1+H% when the higher earner has half the time or less; 2−H% when more). The one-child result is multiplied by 1.6 for two children, 2.0 for three, up to 2.86 for ten.
Who pays child support with 50/50 custody in California?
Usually the higher-earning parent still pays. At H% = 50%, CS = 1.5 × band fraction × (HN − 0.5 × TN), and HN − 0.5 × TN is positive whenever one parent earns more than the other. Example: with $8,000 and $3,000 net incomes and equal time, guideline support is $886.02/month for one child, paid by the higher earner. Support reaches zero only when incomes are equal.
What income does the California formula use?
Net monthly disposable income per §4058–4059: virtually all income (wages, self-employment, rents, pensions) minus actual federal and state income taxes for your true filing status, FICA, mandatory union dues and retirement contributions, health insurance premiums, other court-ordered support paid, and hardship deductions. This calculator asks for net disposable income directly — computing it accurately matters more than any other input, and our federal and California tax calculators can help you estimate the tax pieces.
How do childcare and medical costs work on top of the formula?
Work-related childcare and uninsured healthcare are mandatory add-ons (§4062) split between parents in proportion to their net disposable incomes (§4061) — not automatically 50/50. When computing that proportion, the paying parent's income is first reduced by the base support they pay. Courts can adjust the split.
Is the guideline amount binding on California courts?
It's a rebuttable presumption (§4057). Courts may deviate for extraordinarily high incomes, unusual timeshare arrangements, hardship, or where applying the formula would be unjust — but they must state reasons. In default proceedings with no timeshare evidence, H% is set to 0 or 100 by rule (§4055(b)(6)).
Why is the official California calculator offline?
The DCSS guideline calculator was decertified on December 13, 2025 because its tax tables hadn't been updated for the July 2025 federal tax changes; as of mid-2026 the Judicial Council lists only commercial calculators (Xspouse, CalSupport, Family Law Software) as certified. The §4055 formula itself is unchanged — this calculator implements it directly on the net incomes you enter.