Whenever a Wisconsin court enters a judgment for divorce or legal separation, or issues a custody/placement order in some other action affecting the family, it must make a determination about child support. Wisconsin child support law consists of four basic rules:

1. The fundamental rule, which the court should use unless a reason exists for using one of the other rules or deviating from the results of the fundamental rule, is that of the percentage standards established under Wis. Statute 49.22(9) and published as HSS 80.03 of the Wis. Administrative Code. Under this rule, the noncustodial parent pays child support to the custodial parent based on a percentage of the payer's "base income" (gross income plus any imputed income). The percentage is based on the number of children to be supported, and the percentages are as follows:


• 17% for one child
• 25% for two children
• 29% for three children
• 31 % for four children
• 34% for five or more children


2. A serial payer rule for a payer who has a pre-existing child support obligation for other children.

The rule in effect deducts the amount of any pre-existing child support obligation from the payer's base income before applying the appropriate percentage standard to the adjusted base income for the new child support obligation.

3. A shared-time rule for parents who have shared placement of their children: This rule actually consists of two rules:


• If the parent with less placement time has the children from 31% to 40% of the time, the amount of child support under the percentage standards is reduced according to a table which increases the amount of the reduction with each increase in the percent of time the parent has the children; for example, a parent who has the children 38% of the time has the child support amount reduced to 73.36% of the amount obtained by the percentage standard, whereas a parent who the children 32% of the time has the child support amount reduced to 93.34% of the amount obtained by the percentage standard.
• For parents who share the children so that each parent has the children from between 41% to 59% of the time, child support is determined for both parents based on a reduction of the amount determined under the percentage standards, and then the lesser obligation is deducted from the greater obligation giving a net child support obligation for the parent with the greater obligation. As with the first shared-time rule, the reduction of the child support obligation under the percentage standards is obtained according to a table which increases the amount of the reduction with each increase in the percent of time the parent has the children; for example, a parent who has the children 42% of the time has the child support amount reduced to 60.04% of the amount obtained by the percentage standard, whereas a parent who the children 58% of the time has the child support amount reduced to 6.76% of the amount obtained by the percentage standard. After the reduced obligations are determined for both parents, the lesser obligation is deducted from the greater obligation giving a net child support obligation for the parent with the greater obligation.


4. A split-custody rule for parents who have split the custody of children between them.

   This rule is much simpler than the shared-time rule. The child support obligations are first calculated for both parents based upon the number of children in the other parent's custody, then the child support obligation of the parent with the greater obligation is reduced by subtracting the other parent's obligation from the greater obligation, giving a net child support obligation.



In addition to the above four rules, the court may further modify a child support obligation if it finds by the greater weight of the credible evidence that use of the above rules obtains a result which is unfair to the children or to any of the parties. In making such a determination, the court should consider several relevant factors including the financial resources of both parties, the needs of each party to support himself or herself and other dependents, the earning capacities of both parties, and several other relevant factors.

The Wisconsin Statute governing child support is s. 767.25.