How is child support calculated in Michigan?

What goes into the formula

The 2025 Michigan Child Support Formula Manual, effective January 1, 2025, breaks support into base support, medical support (ordinary and additional medical expenses, health care coverage, and premiums), and child care. Each parent’s net income is the starting point, and the manual says net income is not the same as take-home pay.

Obligations are generally apportioned by each parent’s percentage share of combined net income (2025 MCSF 3.01(B)). Base support comes from the combined net family income and the General Care Support Table in the formula supplement.

Why overnights matter

Base support is adjusted by a parental time offset equation that uses each parent’s approximate annual overnights (2025 MCSF 3.03). If there is no credible evidence that practice has changed, the overnights used in the most recent order are presumed to continue.

That links your parenting time schedule to the support number. Counting real overnights on a calendar is a useful first step before a Friend of the Court review or a support motion.

When a parent earns less than they could

If a parent is voluntarily unemployed or underemployed, income can include the potential income that parent could earn, based on their actual ability and a reasonable likelihood of earning it (2025 MCSF 2.01(G)). The manual lists factors such as work history, education, health, local job availability, and prevailing wages, and says imputation cannot rest on generalized assumptions like full-time minimum wage.

Changing the amount

In a Friend of the Court case, either parent can request a review in writing, though the office does not have to act on more than one request from a party every 36 months (MCL 552.517). A parent can also file a motion on SCAO form FOC 50, and the court may modify on a motion only on finding a substantial change in circumstances (MCL 552.517b(8)).

Support changes can reach back only to the date notice of the petition was given to the other party (MCL 552.603(2)), so timing matters.