Child Support Calculations in Michigan

Michigan uses the Michigan Child Support Formula (MCSF), an Income Shares model with a unique continuous parenting-time adjustment. Governed by MCL 552.605 and the official MCSF Manual and Supplement, the current formula took effect January 1, 2025. Whether you're navigating an uncontested or contested divorce, understanding how Michigan calculates child support is essential.

The Income Shares Model

Michigan's Income Shares model estimates what families at various income levels typically spend on children and allocates that amount between parents based on their respective net incomes. The MCSF General Care Support Tables list base support obligations for combined monthly net family incomes up to $17,747.86. Above this cap, courts exercise discretion based on the child's needs.

The basic calculation process:

• Determine each parent's individual net income
• Combine net incomes to get monthly net family income
• Look up the base support obligation in the tables
• Apportion by each parent's share of family income
• Apply the Parental Time Offset (PTO)
• Add medical support and childcare components

Determining Net Income

Michigan defines income broadly as funds reasonably available for child support. This includes:

• Wages, salaries, commissions, and bonuses (averaged over 12-36 months if variable)
• Self-employment income (with certain deductions added back)
• Rental income, dividends, and interest
• Unemployment, disability, and workers' compensation
• Pensions, retirement benefits, and spousal support received from third parties
• Perquisites and in-kind benefits that reduce living expenses

Excluded from income: Means-tested benefits (TANF, SNAP, SSI), child support received for other children, and employer-paid benefits not deducted from wages.

The Parental Time Offset (PTO)

Unlike many states that use a fixed overnight threshold, Michigan applies a continuous parenting-time adjustment using the PTO formula:

PTO = [Ao^2.5 × Bs − Bo^2.5 × As] ÷ [Ao^2.5 + Bo^2.5]

Where Ao and Bo are each parent's annual overnights, and As and Bs are their base support obligations. Key features:

• No minimum threshold: PTO applies whenever overnights can be determined
• Equal overnights ≠ zero support: The higher earner still pays some support with equal parenting time
• 21+ overnight change: A change of at least 21 overnights per year may justify modification

Estimate Your Michigan Child Support

Use our calculator to get a preliminary estimate. For official calculations, use the Michigan Child Support Calculator.

Low-Income Threshold

Michigan protects low-income obligors through the Self-Support Reserve, set at $1,063 per month net income. Key rules:

• Below $1,063/month: Parent owes 10% of their net income (Low Income Equation)
• Near the threshold: A Low Income Transition Equation smooths the jump to the regular formula
• Sub-LIT parent excluded: When one parent is below the threshold, their income is excluded from the other parent's family income calculation

Medical Support, Childcare, and Add-Ons

Beyond base support, Michigan requires allocation of additional expenses:

• Ordinary Medical Expense (OME): $200/year for one child (scaled by number of children), built into the support calculation
• Health insurance: Coverage is "reasonable" if the net cost doesn't exceed 6% of the providing parent's gross income. Must be accessible within 30 miles/30 minutes
• Uninsured medical: Divided pro rata by income shares
• Childcare: Net costs (after subsidies/credits) shared pro rata; presumed to end when child turns 13

Common Calculation Mistakes

• Using outdated tables: Always use the current MCSF Manual paired with the current Supplement (effective January 1, 2025)
• Expecting a threshold: Michigan's PTO is continuous—there's no fixed overnight count that triggers a different formula
• Forgetting additional children adjustment: If a parent has children from other relationships, apply the multiplier (83% for 1, 75% for 2, 68% for 3, etc.)
• Ignoring dependent benefit credit: Social Security/VA benefits paid to children based on a parent's record reduce that parent's cash obligation
• Not averaging variable income: Bonuses, commissions, and overtime should be averaged over 12-36 months

Modification and Duration

Child support can be modified when circumstances change. The Friend of the Court (FOC) reviews orders at least every 36 months. Modification requires meeting the minimum threshold:

• 10% of current order or $50/month, whichever is greater
• Incarceration: Support is abated after 180+ consecutive days if the parent cannot pay
• Retroactivity limited: File for modification promptly—courts cannot retroactively cancel accrued amounts

Duration: Support ends at age 18, but may continue while the child is regularly attending high school full-time with a reasonable expectation of graduating—never past age 19½.

Enforcement Options

Michigan provides robust enforcement tools:

• Immediate income withholding: Required for most orders; employers remit to MiSDU
• License suspension: Driver's, occupational, and recreational licenses when arrears exceed 2 months
• Liens: Past-due support creates liens on real and personal property
• Tax refund intercepts: State and federal refunds can be seized
• Discretionary surcharge: Courts may impose a surcharge on willful nonpayment (1% + 5-year Treasury rate)

Key Takeaways

• Income Shares + continuous PTO: Michigan uses a unique 2.5-exponent formula with no overnight threshold
• $17,747.86/month cap: Tables apply up to this combined income; above, courts use discretion
• Low-income protection: Self-Support Reserve at $1,063/month; obligors below pay 10% of net income
• Add-ons prorated: OME ($200/year), health insurance (≤6% reasonable cost), and childcare shared by income
• Modification threshold: 10% of current order or $50/month, whichever is greater
• 36-month reviews: FOC must review orders at least every 3 years

For more information about Michigan divorce processes, see our Michigan divorce timeline and filing checklist.