Michigan child support calculator

Michigan is not a simple table you look up. It runs a formula. First it finds each parent’s base support obligation with the General Care Equation: combine both parents’ monthly net incomes, read a base amount and a marginal percentage for that income and number of children from the General Care Support Tables, and multiply by each parent’s share of the combined income. That gives what each parent would owe for the children’s general care.

Then it nets the two obligations against each other after weighting them by parenting time (next sections). The result is a single number: which parent pays, and how much per month.

The base amounts and percentages come from the General Care Support Tables in the 2021 MCSF Supplement — one table per number of children, each with eight income bands from $1,318 up to $10,581 of monthly net family income. For each band there is a base support figure plus a marginal percentage that applies to income above the band’s floor. For example, for two children at $8,000 combined net income the equation uses the $6,830 band ($1,891.91 base + 20.27% over $6,830). This calculator uses those exact figures.

Below the Low Income Threshold ($1,063/month) a parent’s base support is just 10% of income, and a Low-Income Transition caps support just above the threshold — both built in here. When net income runs far above the top band, the court has discretion (MCSF 3.02(E)).

Michigan works from each parent’s monthly net income — not gross. Net income is gross income minus taxes and the specific deductions listed in MCSF Chapter 2 (income taxes, mandatory contributions, certain pre-existing support, and more). Because that determination is detailed, this calculator asks you to enter each parent’s best estimate of monthly net income directly. For a filing-ready figure, work through the Chapter 2 income determination or use the official worksheet.

This is what makes Michigan distinctive. Instead of a flat parenting-time discount, it uses a curved offset equation weighted by each parent’s annual overnights:

offset = [ (A_o)^2.5 × B_s − (B_o)^2.5 × A_s ] ÷ [ (A_o)^2.5 + (B_o)^2.5 ]

where A_o/B_o are each parent’s overnights and A_s/B_s are their base support. The 2.5 exponent means small amounts of parenting time change little, but as a parent approaches equal time the reduction accelerates. When both parents have equal income and equal time, neither pays; when time is equal but incomes differ, the higher earner pays. This calculator applies the equation exactly.

It computes base support — the General Care Equation plus the Parental Time Offset. It does not add the medical and child care obligations, which the court apportions separately by each parent’s income share (ordinary medical is presumed at $454 per child per year). It also doesn’t handle credits for other support obligations, incapacitated-parent adjustments, split custody, or income imputation. For a figure you can file, use the official Michigan worksheet or consult an attorney.