Guideline estimates: income shares, Texas, New York, and California modes
Courts set child support with a formula, not a hunch. 41 states use the income-shares model: combine both parents' incomes, estimate what they'd spend on the kids together, and split that in proportion to income. A few states use a flat percentage of the paying parent's income, and three use the Melson formula.
Defaults are New York's CSSA percentages; most income-shares tables land in the same neighborhood. Your state's exact table governs. Edit the percentage if you know your state's number.
This calculator is for education only and is not legal advice. Courts can and do deviate from guideline numbers. Use your state's official worksheet or calculator for anything you'll file.
| State | Model | Key rule | Worth knowing |
|---|---|---|---|
| California | Statewide formula (Fam. Code §4055) | CS = K × (HN − H% × TN), computed by court-certified software | Parenting time changes the number directly, so the schedule and the payment move together |
| Texas | Percentage of net resources (Fam. Code §154.125) | Flat 20% to 40% of the paying parent's monthly net resources | Net resources capped at $11,700/mo since September 2025; max guideline for 1 child is $2,340 |
| New York | Income shares (CSSA) | 17% to at least 35% of combined income, split pro-rata | Formula applies up to $193,000 of combined income; courts have discretion above it |
| Florida | Income shares (Fla. Stat. §61.30) | Combined income runs through a statutory table | Substantial time-sharing changes the formula |
| Pennsylvania | Income shares | Schedule keyed to the parents' combined net income | Works from net income, so allowed deductions matter |
| Illinois | Income shares (since 2017) | Standardized net-income tables | 146 or more overnights shifts the math to a shared-parenting calculation |
| Ohio | Income shares | Statutory obligation table | Table updated in 2019 |
| Georgia | Income shares (O.C.G.A. §19-6-15) | Combined-income obligation split pro-rata | On the income-shares model since 2007 |
| North Carolina | Income shares | Guideline chart by combined income | Above-chart incomes are handled case-by-case |
| Michigan | Michigan Child Support Formula | Income-shares style manual with a parenting-time offset | More overnights directly reduce the payment |
| New Jersey | Income shares | Appendix IX worksheets | Separate worksheets for sole and shared parenting |
| Washington | Income shares (RCW 26.19) | Economic table sets the basic obligation | Both parents share the obligation pro-rata |
Every state publishes its own guideline, and every state lets judges deviate from it. The table shows the starting point, not the ceiling.
| Children | Texas: % of paying parent's net resources | New York: % of combined parental income |
|---|---|---|
| 1 | 20% | 17% |
| 2 | 25% | 25% |
| 3 | 30% | 29% |
| 4 | 35% | 31% |
| 5+ | 40% | At least 35% |
Texas applies its percentage to one parent's income; New York applies its percentage to both parents' combined income, then splits the result pro-rata. Same-looking numbers, different math.
This calculator estimates guideline child support four ways: a generic income-shares mode that fits most states, plus exact-formula modes for Texas, New York, and California. It's a planning tool. The number a court orders comes from your state's official worksheet, and judges can deviate when the facts justify it.
41 states use income shares: add both parents' incomes, look up the combined obligation, and split it pro-rata. If the paying parent earns 60% of the combined income, they cover 60% of the obligation. A few states, Texas most prominently, charge a flat percentage of only the paying parent's income. Delaware, Hawaii, and Montana use the Melson formula. Whatever the model, health-insurance premiums for the kids and work-related childcare typically get split pro-rata on top of the base number, and courts can impute income to a parent who is voluntarily unemployed or underemployed.
Pick your mode, enter net monthly income (annual for New York), set the number of children, and choose which parent is noncustodial. In income-shares mode the percentage field is editable: it defaults to New York's CSSA numbers, and most state tables land nearby, but your state's exact table governs. California asks for one extra input, the higher earner's share of parenting time, because its formula uses time directly.
Texas: a paying parent netting $6,000 a month with 2 children owes 25%, or $1,500 a month. A high earner netting $15,000 is capped at $11,700 of net resources, so 1 child costs 20% × $11,700 = $2,340 a month, the guideline maximum. New York: combined income of $150,000 with 2 children produces a $37,500 annual obligation at 25%. A noncustodial parent earning $90,000 holds a 60% income share and pays $22,500 a year, about $1,875 a month. California: with the higher earner netting $8,000, combined nets of $11,000, and 20% parenting time, the formula lands near $1,341 a month for 1 child and about $2,146 for 2, using the 1.6 multiplier.
Most states, 41 of them, use the income-shares model: estimate what the parents would spend on the kids if they still lived together, then split that amount in proportion to each parent's income. A few states instead take a flat percentage of the paying parent's income; Texas is the best-known example at 20% to 40% of net resources. Delaware, Hawaii, and Montana use their own variant, the Melson formula.
Nearly everything a parent earns: wages, salary, overtime, bonuses, commissions, and self-employment profits. Many states count investment and rental income too. A parent can't dodge the formula by not working, either. Courts can impute income to a parent who is voluntarily unemployed or underemployed, which means support gets calculated on what they could reasonably earn rather than what they report.
Not if incomes differ. Equal parenting time usually lowers the number, sometimes by a lot, but when one parent earns more, most formulas still order a payment so the kids' standard of living doesn't drop at the lower-earning home. California makes this explicit: parenting time is a variable inside the formula itself, so equal time with unequal incomes still produces a payment.
You can agree, but a judge has to approve it. Child support is legally the child's right, not the parents', so it can't be waived in a private deal, and courts look hard at agreements that come in below the guideline. Get any agreement written into a court order. An informal arrangement isn't enforceable, and it won't stop arrears from building under the existing order.
In most states at age 18, or high-school graduation if that comes later. Several states run longer than that, and New York goes to 21. Orders don't always shut off on their own, either. If an order covers several children, one child aging out usually means going back to court for a recalculation rather than reducing payments on your own.
Go back to the court that issued it and show a material change in circumstances: a job loss, a significant raise, a new parenting schedule. Until a judge signs a modified order, the old amount keeps accruing, and arrears don't vanish. Courts generally won't erase support that already came due, so if your situation changes, file quickly instead of quietly paying less.
This calculator is for education only and is not legal advice. Courts can and do deviate from guideline numbers. Use your state's official worksheet or calculator for anything you'll file.