Wisconsin Serial Family Child Support Calculator

When a parent already owes support under an earlier obligation, Wisconsin adjusts income for that obligation before calculating support in a newer case.^[1] The adjustments run in the order each legal duty began, oldest first, and the newest case gets the standard percentage of what remains. Enter income, each earlier obligation with its date, and the new case's children below, and the calculator walks the ladder step by step.

Two principles carry this whole page. Earlier families come first, in time order, and nothing here changes an existing order. What the adjustment does is keep the newest case from being calculated on income the payer never actually has.

Please read before you start. This is an estimate, not a court order. It applies the serial-family provisions in Wis. Admin. Code § DCF 150.04(1) to the figures you enter, reducing income by an earlier support obligation before the newer one is calculated. The result depends on the earlier order being current and correctly stated. Arrears, a modified order, or an obligation the court declines to credit will move the number. Under Wis. Stat. § 767.511(1m) a court can order a different amount. Using this tool does not create an attorney-client relationship with Sterling Lawyers and nothing here is legal advice.

Built on the serial family provisions in Wis. Admin. Code DCF 150.04(1) and checked against the state's official serial family worksheet and calculator.^[2]

Is this the right calculator for you?

Use it when the paying parent has at least one earlier legal support obligation and a newer case needs a number. Different facts point elsewhere.

• No earlier support obligations. The ladder has nothing to adjust, so support runs on the standard percentages through the main Wisconsin child support calculator.
• The adjustment pulls income into the state's low income schedule. Wisconsin expressly lets courts combine the two provisions when that happens, so carry the adjusted income into the low income child support calculator.
• The new case is shared placement. The final adjusted income from this ladder becomes the starting income in the shared placement child support calculator.
• The new case is split or combined, or adjusted income runs above $7,000. The adjusted income feeds those formulas the same way. The calculator preserves the flags and routes you to the right tool.

How the serial family ladder works

The sequence is strict, and the order is the whole point: each earlier family's claim comes out before the next one's gets measured.

1. List every legal support obligation, oldest first. The date each duty began controls the order, not the date any paperwork was filed.
2. Start with monthly income available for child support. Wisconsin builds that figure from gross income across all sources, with imputation where it applies.^[3]
3. Take the first rung's deduction. For a court-ordered obligation, the deduction is the higher of the order's monthly amount or what the current formula would produce for those children. For a child in the parent's own home, or a prior shared placement order, it is the standard percentage of the income at this step.
4. Subtract, and carry the adjusted income down. Each following rung measures its deduction against what remains, not against the original income.
5. Repeat for every obligation in order. The ladder ends with the final adjusted income.
6. Calculate the new case last. The standard percentage for the new case's children applies to the final adjusted income, or that income feeds the shared, split, high, or low income formula when one of those governs the new case.

The calculator renders each rung with its method and deduction, matching the state's official serial family calculator step for step.^[4]

When does a legal obligation begin?

The clock is not the court date for every child. For a child born during a marriage, the duty begins at birth or adoption. For a child born outside marriage, it generally begins when paternity is legally established, and a mother's duty to her own child at home runs from birth.

The intact family rule surprises people most. A parent supporting a child in their own home right now can have that obligation counted in the ladder even though no court order exists for that child. The duty is real, so the carve-out is real.

A worked example

A parent has $4,800 a month in income available for child support. The oldest obligation is a court order for one child that sets support at $700 a month. The second is one child living in the parent's current home. The new case involves one child.

• Rung one, the court order: the current formula would produce 17% x $4,800 = $816, which is higher than the $700 order, so $816 comes out. Adjusted income: $3,984.
• Rung two, the child at home: 17% x $3,984 = $677. Adjusted income: $3,307.
• The new case: 17% x $3,307 = about $562 per month, instead of the $816 an unadjusted calculation would produce.

Notice rung one. The order says $700, but Wisconsin deducts the higher of the order or the current formula's figure, so the ladder carves out $816. That single rule changes more serial results than any other detail on this page.

What this adjustment does not do

It does not touch older orders. The code says directly that a parent may not use these provisions to seek modification of an existing order based on a later obligation. A new family is not, by itself, a path to shrinking what an earlier family receives.

Changing an older order is a different road entirely, with its own standards and its own filings. If that is what you actually need, that is an attorney conversation, not a calculator.

What this estimate leaves out

Your result is the guideline figure for the newest case only, and the sequence itself is discretionary with the court.

• Older orders. Every existing order stays exactly as written unless a court modifies it on its own merits.
• Combinations. Adjusted income can land in the low income schedule or feed the shared, split, or high income formulas, and blended cases belong with an attorney.
• Medical support and cost decisions. Courts assign health insurance responsibility and related costs separately from this number.
• The order itself. Deviations run in either direction on request with written findings,^[5] and only a court sets, approves, or changes support.

How Sterling Lawyers can help

Parents supporting more than one family carry the most complicated math in Wisconsin's system, and the most judgment calls: which duties count, which dates control, and what each rung deducts. Sterling Lawyers practices family law exclusively across Wisconsin. We sequence obligations correctly, protect the number in the newest case, and keep the older ones from being disturbed by accident.

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