The Parental Time Offset in Michigan Child Support
Michigan nets the two parents’ base support obligations with the Parental Time Offset, weighting each by the other parent’s overnights raised to the 2.5 power, so support falls as the children spend more time with the payer and equal time with unequal incomes still leaves a payment.
The equation
The offset adjusts the base obligations for the costs and savings that follow the children between homes. Each parent’s overnights are raised to the 2.5 power and the obligations are weighted by the other parent’s overnights: (Ao2.5 × Bs − Bo2.5 × As) divided by (Ao2.5 + Bo2.5), where Ao and Bo are the overnights with parents A and B and As and Bs their base obligations. A negative result means A pays and a positive result means B pays (MCSF 3.03).
What it does
Equal time with equal incomes means neither parent pays; equal time with unequal incomes means the higher earner pays some support; a parent who has the children no overnights gets no reduction; and the reduction grows as the children spend more time in that parent’s home.
An example
The family in the worked example:
| Overnights | Monthly support |
|---|---|
| A has 300 overnights, B has 65 | $1,209 |
| A has 250, B has 115 | $995 |
| A has 183, B has 182 (equal time) | $233 |
The amounts include B’s share of ordinary medical expenses.
Counting overnights
Use the approximate annual number of overnights each parent will likely provide, based on past practice where possible; absent evidence of a change, use the number in the last order or in the current custody or parenting time order. Credit overnights the children lawfully and actually spend with a parent even outside the order, but not overnights exercised in violation of an order.
Changing the count
A substantial difference, at least 21 overnights or enough to change the support beyond the modification threshold, lets either parent or the recipient ask the court to modify the order. Every order must say whether it includes an offset and the number of overnights used.
Questions to bring to an attorney
Ask how the court will count overnights and whether the actual schedule differs enough from the order to ask for a change.
When it does not apply
The offset does not apply when a nonparent has custody of a child.
Frequently asked questions
How does the Michigan parental time offset work?
It weighs each parent's base support obligation by the other parent's overnights, each raised to the 2.5 power, so the parent with more nights pays less or receives.
Does equal parenting time end child support in Michigan?
Not when incomes are unequal: the higher earner pays some support.
How are overnights counted in Michigan child support?
By the approximate annual overnights each parent will likely provide, based on past practice or the order.
When can I ask to change support for overnights in Michigan?
When the actual overnights differ from those used by at least 21, or the change exceeds the modification threshold.
Does the offset apply with a nonparent custodian in Michigan?
No. It does not apply when a nonparent has custody of a child.
Official sources
- 2025 Michigan Child Support Formula Manual (effective January 1, 2025)
- 2025 Michigan Child Support Formula Supplement
- MCL 552.605: child support formula
A local family law attorney can review your situation — many offer a free consultation.
This is general information, not legal advice. It is based on the cited Michigan statutes, rules and court opinions, and every case turns on its own facts. Confirm how the law applies to your situation with a licensed Michigan attorney.