California is unusual: there is no guideline table to look your figure up in. Family Code § 4055 states the obligation as algebra, and your share of the overnights sits inside the formula rather than being a discount applied afterwards — so time and income move the number together. This estimator runs that formula and shows each step with the subsection it comes from.
Four questions. The estimate updates as you type, and you can open the working to see which figure drives it.
Net income, not gross: take gross pay and subtract tax, mandatory retirement, union dues, health-insurance premiums and any court-ordered support already being paid.
Count the nights the children sleep at your home. This matters financially: 90 overnights is the threshold for an automatic 10% reduction.
Enter both incomes to see an estimate.
Estimate onlyBasic support before health insurance, child care and medical costs are added. Courts can depart from the guideline figure. Based on Cal. Fam. Code § 4055, last checked 2026-08-25.
A statutory formula unique to California — CS = K[HN − (H%)(TN)] — that folds timeshare directly into the algebra.
Rosa and Daniel share two children. Rosa's net monthly disposable income is $6,000 and Daniel's is $3,000. Rosa has the children 20% of the overnights.
About $2,016 a month, before any deviation a court might order. Daniel's income never appears on its own in the formula; it matters only through the combined total.
California works from net monthly disposable income. Taxes, mandatory union dues, mandatory retirement, health premiums and support already paid for other children come out first. Entering gross pay overstates the result substantially.
Cal. Fam. Code § 4059H% is the higher earner's approximate share of primary physical responsibility. It is not a discount applied at the end — it sits inside K, so a change in overnights moves the figure more than in most states.
Cal. Fam. Code § 4055(b)(1)(D)The statute decides direction arithmetically. A negative result means the lower earner pays its absolute value — which is how a higher earner with most of the parenting time can end up receiving support.
Cal. Fam. Code § 4055(b)(5)If the paying parent's net monthly income is under full-time minimum wage, there is a rebuttable presumption of a reduction. It is a presumption, not a guarantee — a court can decline it.
Cal. Fam. Code § 4055(b)(7)SB 343 replaced the income bands used to find K, effective 1 September 2024. Older calculators and articles still quote the repealed bands and will give a different answer. This page uses the bands in force.
Cal. Fam. Code § 4055(b)(3)Kidtime records every overnight, swap and handover as it happens, so the parenting-time figure behind your support order is evidence rather than an estimate. Free to start.
Open a case through your county's Department of Child Support Services, or ask for a support order inside an existing family law case. DCSS opens a case at no cost and can establish parentage, set the order and enforce it.
Either parent can ask for a modification when circumstances change materially — income, custody time, or another child. There is no waiting period, but the change must be real and ongoing rather than temporary, and support is not adjusted for the period before the request was filed.
Yes, and more than in most states. Timeshare sits inside the formula rather than being a credit applied at the end, so overnights and income move the figure together. The effect is largest around an even split.
Because § 4055 operates on net monthly disposable income. Entering gross pay would overstate the result. Subtract taxes, mandatory retirement, mandatory union dues, health premiums, and support already being paid for other children.
Yes. § 4055(b)(5) decides direction by the sign of the result, so a higher earner with most of the overnights can be owed support by the lower earner.
It runs the same statutory formula, but it is an estimate. A court also weighs deductions, hardship, add-ons for childcare and health costs, and may deviate from guideline. Treat the figure as a starting point, not an order.
This calculator gives an estimate of basic guideline support for general information. It is not legal advice and it is not the figure a court will order — judges can and do depart from the guideline, and the calculation leaves out health insurance, child care and medical costs. For the controlling text see Cal. Fam. Code § 4055, compare against the state's own calculator, and consult a licensed California family-law attorney about your situation. Last reviewed 2026-08-25.