Wisconsin calculates child support as a flat percentage of the paying parent’s gross income: 17% for one child, 25% for two, 29% for three, 31% for four, and 34% for five or more. That percentage-of-income model, set out in DCF 150.035, is the backbone of every order in the state. The math gets more involved when parents share placement, when income sits at either extreme, or when a parent already supports children from an earlier relationship, but the percentage standard is the starting point every time.
What Counts as Gross Income
The calculation runs on gross income, not take-home pay, and Wisconsin’s definition is broad. It covers wages and salaries, interest and investment returns, Social Security disability benefits, unemployment insurance, workers’ compensation that replaces income, and undistributed earnings from any corporation or partnership a parent controls. Veterans’ disability compensation and military housing and food allowances count too, though the portion of military housing pay tied to area-specific variable costs is excluded.1Legal Information Institute. Wisconsin Administrative Code DCF 150.02 – Definitions
Voluntary deferred compensation and employee contributions to retirement accounts are also included, even when those contributions shrink your paycheck. Money you redirect into a 401(k) still reflects your earning power.
What the state does not count: public assistance benefits (including Wisconsin Works cash payments), FoodShare, Supplemental Security Income, foster care payments, and child support received from another case.1Legal Information Institute. Wisconsin Administrative Code DCF 150.02 – Definitions Before any support determination, pull together recent pay stubs, your last tax return, and statements for any investment or business accounts you hold.
The Standard Percentage Calculation
The simplest form of the formula applies when one parent has the child for more than 75% of overnights in a year. The other parent pays a percentage of their gross monthly income, and the custodial parent’s income does not enter the equation.
- One child: 17% of gross monthly income
- Two children: 25%
- Three children: 29%
- Four children: 31%
- Five or more children: 34%
These are applied to gross income, not take-home pay.2Wisconsin State Legislature. Wisconsin Administrative Code DCF 150.035 – Determining the Child Support Obligation A parent earning $5,000 per month in gross income with two children would owe $1,250 per month in base support, before any adjustments for health insurance or variable costs.
The Shared-Placement Calculation
When each parent has the child for at least 25% of overnights per year (a minimum of 92 days), Wisconsin uses a two-income formula that reflects the real costs of running two households for the same child.2Wisconsin State Legislature. Wisconsin Administrative Code DCF 150.035 – Determining the Child Support Obligation
The shared-placement calculation runs in four steps:
- Multiply each parent’s gross income by the standard percentage for the number of children.
- Multiply each result by 150%. The administrative code explains that this bump accounts for duplicated household costs such as maintaining a bedroom, clothing, and personal items in two homes.3Wisconsin State Legislature. Wisconsin Administrative Code DCF 150.04(6)(b) – Shared-Placement Formula
- Multiply each parent’s adjusted figure by the percentage of time the other parent has placement.
- Compare the two numbers. The parent with the higher obligation pays the difference to the other.
A worked example makes it concrete. Parent A earns $6,000 per month with 60% of placement; Parent B earns $4,000 per month with 40%. With one child the 17% rate applies. Parent A’s figure: $6,000 × 17% × 150% × 40% = $612. Parent B’s figure: $4,000 × 17% × 150% × 60% = $612. Here the two happen to match, so no payment changes hands. Shift either the income or the placement split, and a payment flows from the higher-obligation parent to the other.
Split Placement and Serial-Family Parents
Two common variations have their own worksheets. In a split-placement family (more than one child, with each parent having primary placement of at least one), the obligation is calculated separately for each parent based on the number of children living with the other parent, and the amounts are offset.4Wisconsin Department of Children and Families. Tools to Estimate Income and Support Amounts The higher-obligation parent pays the difference.
A serial-family parent is one who already pays support for children from an earlier relationship. Wisconsin subtracts that existing obligation from gross income before calculating the newer one; the first order uses full gross income, the second uses what remains after the first, and so on.5Wisconsin Department of Children and Families. Serial-Family Parent Worksheet to Estimate Support Courts have discretion over whether to apply this adjustment, and the order of obligations follows the dates each support duty began.
Adjustments for Low and High Incomes
Applying the flat percentages to a very low income can push a parent below subsistence, so Wisconsin uses a reduced-rate schedule for payers earning between 75% and 150% of the federal poverty guidelines.6Wisconsin State Legislature. Wisconsin Administrative Code DCF 150.04 – Determining the Child Support Obligation The schedule, in DCF 150 Appendix C, is updated each year.7Wisconsin State Legislature. Wisconsin Administrative Code DCF 150 Appendix C – Child Support Obligation of Low-Income Payers Using the 2026 federal poverty guideline of $15,960 for a single person, the low-income formula kicks in at a monthly income of roughly $998 (75% of the guideline) and runs up to about $1,995 (150%).8U.S. Department of Health and Human Services. 2026 Poverty Guidelines – 48 Contiguous States Below the 75% floor, the court has discretion to set whatever amount fits the payer’s total circumstances.
At the top of the income scale, a judge is not required to apply the full standard percentage to every dollar. The court can find that the formula produces an amount that exceeds the child’s actual needs and order a lower figure, but it must put its reasoning on the record, including what the standard calculation would have produced and why it departed from that number.9Wisconsin State Legislature. Wisconsin Statutes 767.511(1n)
Imputed Income If a Parent Is Unemployed or Underemployed
A parent who quits a job or cuts hours to shrink the support figure will not get far. When a parent is voluntarily unemployed or underemployed without good cause, the court can assign an income based on earning capacity instead of actual earnings.10Wisconsin State Legislature. Wisconsin Administrative Code DCF 150.03(3)
To set that figure, the court looks at recent work history, prior earnings, education, job skills, training, how hard the parent has actually looked for work, and barriers such as homelessness, lack of a driver’s license, substance dependence, or immigration status. One protection matters: incarceration cannot be treated as voluntary unemployment when setting or modifying support.10Wisconsin State Legislature. Wisconsin Administrative Code DCF 150.03(3)
If you’re staying home to care for a young child, that doesn’t automatically trigger imputed income. The court weighs whether childcare costs would eat up most of what you’d earn by working, and whether a child with unusual emotional or physical needs requires your presence at home.
Health Insurance and Variable Costs on Top of the Base
The percentage calculation produces the base monthly support amount. Health insurance and “variable costs” are separate line items added on top. Variable costs include things like work-related childcare and out-of-pocket medical expenses for the child, and the court usually assigns each parent a share proportional to income.
For health insurance, Wisconsin generally expects the parent with access to a reasonable employer plan to cover the child. A plan is considered reasonably priced when the cost does not exceed roughly 10% of the insuring parent’s income. When neither parent has affordable coverage, the court can order a contribution toward premiums or direct that the child be covered through BadgerCare or another public program.
When a Judge Deviates from the Formula
A judge can set support above or below the standard percentages, but only after finding that the formula would be unfair to the child or to a parent. The deviation has to be explained on the record, including the standard amount, the amount ordered instead, and the reasoning behind the change.11Wisconsin State Legislature. Wisconsin Statutes 767.511(1n) – Deviation from Standard
The statute lists factors the court may weigh:
- The child’s physical, mental, and emotional health needs, including any special educational expenses.12Wisconsin State Legislature. Wisconsin Statutes 767.511(1m) – Factors
- Extraordinary travel costs for placement exchanges when parents live far apart.
- Whether it is desirable for the custodial parent to stay home as a full-time caregiver, and what childcare would cost if that parent worked.
- Other people the parent is legally obligated to support.
- Each parent’s education, training, work experience, and access to jobs in their area.
- Tax consequences for each parent, and the best interests of the child.
A catch-all permits the court to consider any other relevant factor. In practice, the most common deviations involve shared placement arrangements that the standard formula handles awkwardly, pre-existing support duties, and expensive medical or educational needs.