Child support in the United States is set state by state, under guidelines that are presumptive rather than automatic. The percentage tables look similar across states, but the income they apply to, the caps above which they stop, and the way the second parent income counts are all different, and those differences are worth real money every month.

No national formula: why the state decides everything

Child support in the United States is a state matter, and the federal role is mostly to require that each state have guidelines and to set the enforcement machinery that collects what courts order. Every state must have a guideline, the guideline amount is presumptively correct, and a court that departs from it must say why on the record. Beyond that common frame, the states diverge sharply. Some apply a percentage to one parent income. Some combine both parents incomes and split the result. Some use a table built from estimates of what intact families spend on children. The result is that the same two parents, with the same incomes and the same children, can face materially different guideline amounts depending on which side of a state line the case is filed, and a number carried across state lines without checking the method behind it is not an estimate at all.

The divergence has a history. Before guidelines, support amounts varied wildly between judges in the same courthouse, and the federal Family Support Act of 1988 pushed states toward written formulas to make outcomes more predictable and more consistent. States chose different formulas, and the differences hardened into the three broad families described below. Percentage-of-income models are the simplest to explain and the easiest to compute by hand. Income-shares models, used by the majority of states, try to replicate what the parents together would have spent on the children had they lived together, then divide that total between them. Melson-style models, used in a small number of states, start from the parents basic needs and allocate what remains. None of these is the true amount in any scientific sense. Each is a policy choice about how to share the cost of raising children between two households, expressed as arithmetic so that it can be applied consistently.

That policy character is why guideline amounts should be read as starting points. A guideline is presumptive, which means the court starts there and departs only for reasons the statute recognises, stated on the record. The reasons include the child special needs, extraordinary medical or educational costs, the parents very high or very low income, and the time each parent actually spends caring for the child. They do not include a general sense that the amount feels high or low. Anyone using an online estimate should therefore treat it as a planning figure for the conversation with a lawyer or an agency, not as a prediction of an order. The calculator on the Child Support Calculator page prices the three published formulas it models, Texas, New York, and Wisconsin, and labels everything else as what it is: a comparison figure from another state method, not your state number.

The three models side by side

The three models in this guide differ in three choices: whose income counts, what is done with it, and where the formula stops. Texas counts only the paying parent, the obligor, and applies a percentage to that parent monthly net resources. The other parent income does not enter the calculation, except through the court discretion to depart from the guideline. New York counts both parents, combines their incomes, applies a percentage to the combined figure, and then divides the result between the parents in proportion to their incomes, so that the noncustodial parent pays their share. Wisconsin counts the paying parent income available for support and applies a percentage standard to it, with a separate shared-placement formula when both parents have substantial placement time. All three use percentages that rise with the number of children, but the percentages apply to different income definitions, so the tables cannot be compared percentage to percentage without doing the arithmetic.

The table invites a misreading, and it is worth naming. New York 17 percent and Wisconsin 17 percent for one child are not the same 17 percent, because New York applies it to combined income and then takes a share, while Wisconsin applies it to one parent income directly. Texas 20 percent looks higher than both, but it applies to net resources, which is income after specified taxes and deductions, not to gross pay. Comparing percentages across models without their income definitions is like comparing prices in different currencies without an exchange rate. The worked comparison later in this guide does the conversion, by pricing the same family under all three methods, so the differences can be seen in dollars rather than inferred from percentages.

Texas: a percentage of net resources, with a cap

Texas Family Code section 154.125 sets the guideline as a percentage of the obligor monthly net resources. Net resources is a defined term, not a synonym for take-home pay. It starts with gross income from nearly all sources: wages, salary, self-employment income, rental income, interest, dividends, and most benefits. From that total, the statute subtracts Social Security taxes, federal income tax computed at the single rate, state income tax, union dues, and the cost of health and dental insurance for the children. What remains is net resources, and the percentage applies to it. The Texas Attorney General publishes tax charts that convert gross pay to net resources for the common cases, because the federal tax step, computed as if the obligor filed singly, is not a figure most people carry in their heads.

The percentage schedule is: 20 percent for one child, 25 percent for two, 30 percent for three, 35 percent for four, and 40 percent for five, with not less than the five-child amount for six or more. The schedule applies to monthly net resources from $1,000 up to a cap. Below $1,000 a month, a low-income schedule replaces it: 15 percent, 20 percent, 25 percent, 30 percent, and 35 percent. The cap is recalculated for inflation every six years and published in the Texas Register. The cap in effect since September 1, 2025 is $11,700 of monthly net resources, raised from $9,200. Above the cap, the percentage applies to the capped portion, and any additional support must be justified by the proven needs of the child under section 154.126. The guideline table itself therefore produces at most $2,340 a month for one child, which is 20 percent of $11,700, and any figure above that is a court decision on evidence, not a formula output.

Two adjustments deserve emphasis because they are often missed. First, when the obligor has children in more than one household, section 154.128 adjusts the percentages downward through a defined computation, rather than leaving the matter to discretion. A parent paying for one child before the court while also supporting one other child elsewhere does not pay the full 20 percent; the schedule is reduced to reflect the other obligation. Second, possession time is not a formula input in Texas. The statute sets no overnight threshold that automatically changes the amount. The amount of possession and access time is one factor a court may consider when departing from the guideline under section 154.123, but it does not enter the percentage calculation itself. A parent who expects equal time to halve the Texas guideline figure will be surprised, and the surprise is expensive if it shapes a negotiation.

New York: combined income, shared in proportion

New York Child Support Standards Act, Domestic Relations Law section 240(1-b) and Family Court Act section 413, starts from both parents. Each parent gross income, as reported or as it should have been reported on the most recent federal return, is reduced by Social Security and Medicare taxes and by New York City and Yonkers taxes where applicable, to give each parent income for the calculation. The two incomes are added to give combined parental income. The CSSA percentage is applied to combined income up to a cap: 17 percent for one child, 25 percent for two, 29 percent for three, 31 percent for four, and no less than 35 percent for five or more. The result is the basic child support obligation, which is then divided between the parents in proportion to their incomes. The noncustodial parent share is the amount ordered, paid to the custodial parent.

The cap matters, and it moves. Combined income up to $193,000 a year, effective March 1, 2026, is subject to the percentage schedule as of right. Above the cap, the court may apply the percentage to the excess, consider the statutory factors, or do both. The cap is adjusted periodically, so any figure quoted without its date is suspect. Below the cap, the arithmetic is mechanical, and a worked example shows the sharing clearly. Suppose the custodial parent earns $60,000 and the noncustodial parent earns $90,000, a combined $150,000, with two children. The CSSA percentage is 25 percent, giving a basic obligation of $37,500 a year. The noncustodial parent share is 90,000 divided by 150,000, or 60 percent, so the ordered amount is $22,500 a year, or $1,875 a month, before add-ons. The same combined income split differently between the parents gives a different ordered amount, which is the point of the model: the obligation follows the parents relative resources, not one parent alone.

Add-ons sit on top of the basic obligation in New York. The noncustodial parent pays a pro-rata share of child care expenses incurred because the custodial parent works or attends school, of unreimbursed health care expenses, and of educational expenses, and the court orders a share of health insurance costs. These are mandatory in the sense that the statute requires them to be addressed, though their size depends on the actual expenses. A New York estimate that quotes only the basic obligation understates the order, sometimes substantially, when child care costs are large. Parents can agree to opt out of the CSSA, setting an amount above or below the guideline, but the opt-out requirements are strict, and the agreement must show that the parties were advised of the guideline amount and the reasons for departing from it.

Wisconsin: a percentage standard, with shared-placement rules

Wisconsin percentage standard, in administrative code DCF 150, applies percentages to the paying parent monthly income available for child support, which is gross income adjusted for items the code specifies, including taxes and support paid for other children. The standard is: 17 percent for one child, 25 percent for two, 29 percent for three, 31 percent for four, and 34 percent for five or more. Unlike New York, the Wisconsin percentages for one through four children match the CSSA figures exactly, which tempts readers to treat the two states as interchangeable. They are not, because Wisconsin applies its percentages to one parent income, while New York applies them to combined income and then shares the result. The same family priced under both methods gives different answers, as the worked comparison below shows.

Wisconsin also has the most fully specified shared-placement machinery of the three states in this guide, and it is where the 50/50 question gets its most precise answer. When each parent has court-ordered placement for at least 25 percent of the time, the shared-placement formula applies. Each parent gross monthly obligation is computed from their own income, the two obligations are combined, each parent share is adjusted by the time the child spends with the other parent, and the parent owing the larger amount pays the difference. The formula uses overnights, counted over 365 days, with equivalent overnights for substantial daytime care. At exactly equal time, the parent with the higher income still pays, because the formula equalises the resources available to the child in each household rather than cancelling the obligation. The companion article on 50/50 custody works a full shared-placement example with numbers, and explains why equal time reduces but does not eliminate support when incomes differ.

Wisconsin provides low-income and high-income adjustments alongside the standard. At low incomes, the percentage standard is reduced so that the paying parent retains a self-support amount. At high combined incomes, the code provides a formula that phases the percentage down as income rises, rather than a hard cap of the Texas kind. The details are in DCF 150.04, and any estimate that applies the flat 17 percent to a very high or very low income without those adjustments is incomplete. As in every state, the court may deviate from the standard for reasons stated on the record, including the child special needs and the parents circumstances.

The same family, three guideline numbers

Take one family and price it three ways. The paying parent, Parent A, has monthly gross income of $6,000. The other parent, Parent B, has monthly gross income of $4,000. There are two children, living mainly with Parent B, and no add-on expenses are counted in this comparison. The figures below are simplified: each method real income definition involves tax and deduction steps that the calculator on the hub page models in full, and the comparison uses rounded income definitions to isolate the effect of the formulas themselves. Treat the comparison as a demonstration of the formulas, not as a prediction for any real family.

The spread is $250 a month between the lowest and highest, or $3,000 a year, for the same family, the same children, and the same incomes. None of the three numbers is wrong. Each follows its state law correctly on the stated assumptions. The lesson is that a child support number without a state and a method attached to it is incomplete information, and that moving a case across a state line, where jurisdiction rules allow it, changes the answer by an amount that matters to a household budget. It is also why the hub calculator asks for the state first, before any income figure: the state chooses the formula, and the formula chooses what the income figures mean.

What the percentage leaves out: add-ons and deviations

Every guideline in this guide produces a basic amount, and in every state the order usually contains more than the basic amount. Health insurance premiums for the children, unreimbursed medical expenses, child care costs that enable a parent to work, and educational expenses are commonly added, shared between the parents in proportion to income or as the court directs. In Texas, the children health and dental insurance costs are subtracted in computing net resources, which lowers the basic amount, and the court orders coverage separately. In New York and Wisconsin, add-ons are ordered on top of the basic obligation. Either way, a family with $1,200 a month in child care costs faces a materially different order from a family with none, and no percentage table captures that difference on its own.

Deviations are the second layer. A court may order more or less than the guideline for the child special needs, for extraordinary expenses, for a parent very high or very low income, for the time the child spends with each parent beyond the standard schedule, and for other factors the statute lists. The deviation must be explained on the record, with findings that show why the guideline amount would be unjust or inappropriate. Deviation is not a negotiation tactic; it is a judicial finding on evidence. Parents who agree a different amount can usually do so, subject to the court approval and, in New York, the strict opt-out requirements noted above. An estimate that ignores deviations will be right for the standard case and wrong for every case that is not standard, which is a large share of real cases.

Other states: income-shares tables and why estimates vary

Most other states use income-shares models. The state publishes a table, or a formula that generates one, giving the total support obligation for each combined income level and number of children, based on economic studies of what intact families spend on children. The parents combined income locates the row, the table gives the total, and the total is split in proportion to income, with adjustments for parenting time, insurance, and child care. The tables differ by state because the underlying expenditure studies, the income ranges, and the adjustments differ. Two income-shares states can therefore give different answers for the same family, just as the three percentage states do, though the mechanism is a table rather than a percentage.

That is why an other-states estimate from any calculator, including the one on the hub page, must be labelled as a comparison figure, not a state figure. It may use a representative income-shares table or another state method as a stand-in, and it cannot know the destination state table, its parenting-time adjustment, or its deviation rules. The honest use of such a figure is to sense-check the scale of support, to prepare for a conversation, and to motivate looking up the actual state guideline, worksheet, or official calculator. Every state publishes its guideline, worksheet, or calculator through its courts or child support agency, and those official sources are the only ones that settle what a case will produce. This article names no other-state figure as authoritative, because none is.

Checking an estimate before relying on it

Check any child support estimate in five steps. First, confirm the state and the method: percentage of one parent income, combined income shared, or income-shares table. Second, confirm the income definition: gross, net resources, or income available, and which deductions were taken. A figure computed on gross pay cannot be compared with one computed on net resources. Third, confirm the cap and its date: Texas $11,700 since September 1, 2025, New York $193,000 from March 1, 2026, and any other state cap from its current worksheet. Fourth, add the add-ons: insurance, child care, medical, and educational costs, shared as the state directs. Fifth, ask about deviations: special needs, extraordinary costs, parenting time beyond the standard, and income far above or below the ordinary range. An estimate that survives all five checks is a useful planning figure. One that fails any of them is a number in search of a method, and the method is what the court will apply.

Child support orders also change. Incomes change, children age, parenting schedules change, and guidelines are revised. Most states allow modification on a substantial change of circumstances, and some allow review on a fixed cycle. An estimate is therefore a snapshot, dated by the guideline version it used, and it should be re-run when circumstances change rather than carried forward as a permanent figure. Keep the worksheet, keep the inputs, and keep the date. When the order arrives, compare it with the estimate line by line, and ask about every line that differs. That comparison, more than any single number, is what turns an estimate into understanding, and understanding into a case that can be argued on its actual facts.

Frequently asked questions

How is child support calculated in the United States?

There is no national formula. Each state writes its own guideline. Texas applies a percentage to the paying parent monthly net resources, New York applies CSSA percentages to combined parental income and shares the result, and Wisconsin applies a percentage standard to the paying parent income available for support. Most other states use income-shares tables.

What percentage of income is child support in Texas?

For monthly net resources from $1,000 up to the $11,700 cap, Texas applies 20 percent for one child, 25 percent for two, 30 percent for three, 35 percent for four, and 40 percent for five or more. Below $1,000 a month, a lower schedule of 15, 20, 25, 30, and 35 percent applies.

How does New York calculate child support?

New York combines both parents incomes, applies the CSSA percentage to combined income up to the $193,000 cap, and divides the basic obligation in proportion to income. The percentages are 17 percent for one child, 25 percent for two, 29 percent for three, 31 percent for four, and no less than 35 percent for five or more. Add-ons for child care, health care, and education are ordered separately.

What are Wisconsin child support percentages?

Wisconsin percentage standard is 17 percent for one child, 25 percent for two, 29 percent for three, 31 percent for four, and 34 percent for five or more, applied to the paying parent monthly income available for child support. A separate shared-placement formula applies when each parent has at least 25 percent of the placement time.

Is the guideline amount the final child support order?

Usually it is the starting point. The guideline amount is presumptively correct, but courts can depart from it for reasons stated on the record, such as the child special needs, extraordinary expenses, very high or very low income, and parenting time. Add-on expenses for insurance, child care, and medical costs are also ordered on top of the basic amount in most states.

Does child support change if the parents live in different states?

The case is governed by the law of the state with jurisdiction, and enforcement across state lines runs through the Uniform Interstate Family Support Act. The guideline of the issuing state controls the amount, so the same family can face different amounts depending on which state issues the order. Confirm jurisdiction and the applicable guideline before relying on any estimate.