Chapter 3: Calculating Each Parent’s Obligation

The next step in determining each parent’s child support obligation is to calculate the components of each parent’s support obligation based on their net income as determined in MCSF Chapter 2.

3.01​Child Support Obligations

3.01(A)​A parent’s child support obligation consists of:

(1)​a base support obligation (§3.02) adjusted for parenting time (§3.03);

(2)​medical support obligations that include ordinary and additional (extra-ordinary) medical expenses (§3.04), health care coverage and division of premiums (§3.05); and

(3)​child care expense obligations (§3.06).

3.01(B)​Generally, support obligations should be apportioned between the parents based on each parent’s percentage share of their combined net incomes.

(1)​When calculating the percentage to use to apportion the base support obligation, medical support, and childcare obligations, round the resulting percentages to the nearest hundredth percent.

(2)​Courts may exercise discretion and apportion a parent’s obligation percentage to zero in the following circumstances: (a) subject to §4.02, when a parent is incapacitated; or (b) when a parent has zero income, the total support order is set to $0, and the parent does not have an ability to pay or work.

3.02​Base Support Obligation

3.02(A)​To even out support amounts for children of the same parents, whether ordered in one case or multiple cases, calculate base support using the total number of children-in- common.

(1)​If less than all of the children-in-common are included, then the present case’s base support and the parental time offset (§3.03) is its children’s per capita share of what the amount would be if all of the children-in-common were included on one case.

(2)​When some of the children-in-common are in a nonparent’s custody, calculate the base support for the children in a parent’s custody separately from the base support for those who live with a nonparent-custodian. §2.08(A) and §4.01.

3.02(B)​General Care Equation

(1)​Determine the monthly family income by combining the parents’ net incomes. Only include a parent’s net income if it exceeds the Low Income Threshold (§2.09).

(2)​Solve the following equation using the General Care Support Table (found in the supplement) for the appropriate number of children that the parents have in common and its amounts and percentages from the highest monthly income level that does not exceed the family’s net monthly income.

{ A + [ B x ( C – D ) ] } x E = G  

A = Base Support (General Care Support table, column 3)

B = Marginal Percentage (General Care Support table, column 4)

C = Monthly Net Family Income (§3.02(B)(1))

D = Monthly Income Level (General Care Support table, first column)

E = Parent’s Percentage Share of Family Income (§3.01(B)(1))

G = Base Support obligation using the General Care Equation (round to the nearest whole dollar)

(3)​Subject to §3.02(D), when a parent’s net income exceeds the Low Income Threshold (§2.09(A)), that parent’s base support obligation is the amount determined using the General Care Equation.

(4)​In most instances when a family’s net monthly income exceeds the highest income level in the current supplement’s General Care Support Tables, the parents’ base support obligations will be determined using the General Care Equation. However, when a family’s net income greatly exceeds the highest income level, the court may exercise discretion as provided in §3.02(E).

3.02(C)​Low Income Equation

When a parent’s monthly net income does not exceed the Low Income Threshold, the parent’s base support obligation is 10 percent of that parent’s income. The Low Income Equation is designed to retain funds for the parent’s subsistence.

F x 10% = L

F = Parent's Monthly Net Income, when below the Low Income Threshold (§2.09(A))

10% = Percentage for Income below the threshold

L = Base Support (round to the nearest whole dollar)

3.02(D)​Low Income Transition Equation

When a parent’s net income exceeds the Low Income Threshold, that parent’s base support obligation will generally be determined using the General Care Equation. However, if the following equation’s result is lower than the amount calculated using the General Care Equation, a parent’s base support obligation is the amount determined by applying this equation. The Low Income Transition Equation is designed to balance a parent’s subsistence needs with the costs of raising children in another household.

(H x 10%) + [(I - H) x P] = T

H = Low Income Threshold (§2.09(A))

10% = Percentage for Income below the threshold (§3.02(C))

I = Parent's Monthly Net Income

P = Percentage Multiplier for the appropriate number of children from the Transition Adjustment table

T = Base Support obligation using the Low Income Transition Equation

3.02(E)​Extremely High Family Incomes

(1)​The court should exercise discretion when a family’s income used to calculate support greatly exceeds the highest “Income Amount” in the General Care Support Tables found in the current supplement to this manual.

(2)​When exercising discretion and trying to arrive at an appropriate result in an extremely high-income case, provided the result meets each child’s needs, the court may calculate the child support amounts by using the “Base Support” from the appropriate General Care Support Table and other marginal percentages, or choose to fashion another outcome that financially benefits the children and protects each child’s interests in the inherent obligation each parent owes to the child. See 2025 MCSF-S 2.03(B).

3.03​Adjusting Base Obligation with the Parental Time Offset

3.03(A)​Presuming that as parents spend more time with their children they will directly contribute a greater share of the children’s expenses, a base support obligation needs to offset some of the costs and savings associated with time spent with each parent. (The supplement to this manual contains a graph and other information about adjusting support payments for parenting time.)

(1)​Base support mainly considers the cost of supporting a child who lives in one household. When a parent cares for a child overnight, that parent should cover many of the child’s unduplicated costs, while the other parent will not have to spend as much money for food, utility, and other costs for the child.

(2)​Apply the following Parental Time Offset Equation to adjust base support to reflect some of the cost shifts and savings associated with the child spending time with both parents:

(Ao )2.5· (Bs ) - (Bo )2.5· (As )

(Ao )^2.5 + (Bo )^2.5

A_o = Approximate annual number of overnights the children will likely spend with parent A

B_o = Approximate annual number of overnights the children will likely spend with parent B

A_s = Parent A’s base support obligation

B_s = Parent B’s base support obligation

Note: A negative result means that parent A pays and a positive result means parent B pays.

3.03(B)​Application

(1)​An offset for parental time generally applies to every support determination whether in an initial determination or subsequent modification whether or not previously given.

(2)​The parental time offset does not apply when a nonparent has custody of a child. (§4.01(A)).

3.03(C)​Apply the parental time offset to adjust a base support obligation whenever the approximate annual number of overnights that each parent will likely provide care for the children-in-common can be determined. When possible, determine the approximate number based on past practice.

(1)​When different children spend different numbers of overnights with the parents, use the average of the children’s overnights.

(2)​Absent credible evidence of changed practices, presume the same approximate number that was used in determining the most recent support order.

(3)​In cases without a past determination or other credible evidence, presume the approximate number of overnights granted in the terms of the current custody or parenting time order.

(4)​Credit a parent for overnights a child lawfully and actually spends with that parent including those exercised outside the terms of the currently effective order. This may happen by agreement, or when one parent voluntarily foregos time granted in the order. Do not consider overnights exercised in violation of an order.

(a)​If a parent produces credible evidence that the approximate number exercised differs from the number granted by the custody or parenting time order, credit the number according to the evidence without requiring someone to formally petition to modify the custody or parenting time order.

(b)​When the most recent support order deviated based on an agreement to use a number of overnights that differed from actual practice, absent some other change warranting modification, credible evidence of changed practices only includes an order changing the custody or parenting time schedule.

3.03(D)​If a substantial difference occurs in the number of overnights used to set the order and those actually exercised (at least 21 overnights or that causes a change of circumstances exceeding the modification threshold (§4.05)), either parent or a support recipient may seek adjustment by filing a motion to modify the order.

3.03(E)​So the court can know if circumstances have changed at the time of a subsequent determination, every child support order must indicate whether it includes a parental time offset and the number of overnights used in its calculation.

3.04​Medical (Health Care) Obligations

3.04(A)​Obligations Generally

(1)​The term “medical” includes treatments, services, equipment, medicines, preventative care, similar goods and services associated with oral, visual, psychological, medical, and other related care, provided or prescribed by health care professionals for the children.

(2)​Routine remedial care costs for children (e.g., first-aid supplies, cough syrup, and vitamins) do not qualify as medical expenses.

(3)​Every support order should specify the medical expense percentage based on each parent’s share of the family income (§3.01(B)(2)) for uninsured medical expenses for which each parent is responsible.

(4)​Ordinary medical expenses include the support recipient’s co-payments and deductibles, and uninsured medical-related costs for all children in this case. Ordinary medical expenses presume that the recipient is the individual who typically obtains medical care for the children for whom support is paid, and therefore normally has out-of-pocket expenses needing reimbursement.

(5)​Additional (extra-ordinary) medical expenses consist of the support recipient’s out-of-pocket expenses that exceed the children’s ordered annual ordinary medical expense amount and (because the payer is reimbursing the payee in advance for the support payer’s share of anticipated ordinary medical expenses) any of the support payer’s uninsured medical expenses.

(6)​A parent’s or custodian’s qualifying medical expenses include those paid with monies from a health savings account or flexible benefit account, provided that account is funded, in whole or part, with monies reported as that individual’s income.

3.04(B)​Ordinary Medical Expense Obligations

(1)​In order to reimburse the support recipient’s qualifying medical expenditures for the children within the same calendar year, almost every support order should set an appropriate annual ordinary medical expense amount for the children and apportion payment of the annual amount between the parents according to each parent’s percentage share of family income.

(2)​When setting the annual amount, presume that the amount listed for the appropriate number of children in Ordinary Medical Expense Average Table (found in the supplement) is the amount that will be spent on ordinary medical expenses. Amounts may be added to the Table amounts to compensate for higher uninsured expenses that can be predicted in advance (e.g., orthodontia, special medical needs, or ongoing treatments).

(3)​Typically, the court should exercise discretion and determine that no ordinary medical expense amount is appropriate and treat all qualifying medical expenses as additional medical expenses (§3.04(A)(4)) when any following circumstance exists: (a) both parents routinely take one or more children-in-common for medical care and incur qualifying medical expenses; (b) the support payer will likely incur most qualifying out-of-pocket costs for the children; (c) an incapacitated payer’s base support obligation is set at zero (§4.02); or (d) the recipient has an employer-paid benefit (e.g., health reimbursement arrangement) that pays the recipient’s initial out-of-pocket expenses for the children.

(4)​Ordinary Expense Payments

(a)​The annual ordinary medical expense amount restarts every calendar year and remains in effect with the rest of the support obligation or until further order of the court.

(i)​The support payer’s apportioned share of ordinary medical expenses should be ordered paid as part of the monthly support obligation and maintained by the support recipient.

(ii)​The support recipient’s apportioned share of ordinary expenses is directly contributed by the recipient as expenses occur.

(b)​Ordinary Medical Expense Accounting

(i)​All qualifying expenditures are considered made in proportion to each parent's medical expense percentage established in the order.

(ii)​Presume that the annual amount will be spent. The recipient does not have to routinely provide proof of its expenditure.

(iii)​In order for a support recipient to seek reimbursement of additional medical expenses, the recipient needs to show that the ordered total annual ordinary medical expense amount for all children was exceeded.

(c)​Prorate ordinary medical expense amounts for partial periods during which they are in effect.

3.04(C)​Additional (Extra-ordinary) Medical Expenses

Additional expenses should be apportioned between the parents according to the medical expense percentages established in the support order.

3.04(D)​Unreimbursed Medical Expense Minimum Enforcement Threshold

(1)​State law establishes that complaints seeking enforcement of unreimbursed additional medical expenses (§3.04(A)(4)) must meet a minimum threshold before a friend of the court office is required to act on that complaint. MCL 552.511a.

(2)​The “minimum enforcement threshold” under MCL 552.511a(1)(b) for additional medical expenses is $100 per child each calendar year, or a lower amount set by the court. If unreimbursed additional expenses do not exceed the threshold before a year ends, those expenses may be submitted to the FOC for enforcement before the deadline under MCL 552.511a(1)(c).

3.05​Health Care Coverage Obligation and Premiums

3.05(A)​Health Care Coverage, Accessibility, and Cost

(1)​The Support and Parenting Time Enforcement Act defines health care coverage as “a fee for service, health maintenance organization, preferred provider organization, or other type of private health care coverage or public health care coverage.” MCL 552.602(n) 

(a)​Private coverage means health care coverage obtained through an employer or purchased by an individual from an insurer.

(b)​Public coverage means health care coverage that is established or maintained by a local, state, or federal government like Medicaid or SCHIP.

(2)​Reasonable Cost of Coverage

Except as otherwise ordered by the court, a reasonable cost to a parent for providing health care coverage for the children does not exceed 6 percent of the providing parent’s gross income. In applying this standard, the cost of providing health care coverage is the parent’s net cost of adding the children to the parent’s coverage (e.g., difference between self-only and family coverage) or adding the children to the existing coverage.

(a)​Parents with a net income below 133 percent of the federal poverty level or whose child is covered by Medicaid based on that parent’s income should not be ordered to contribute toward or provide coverage, unless coverage is obtainable without any financial contribution by that parent.

(b)​A parent’s cost for providing health care coverage is unreasonable if the parent’s total current obligation for support, child care expenses, ordinary health care expenses, plus the parent’s net share of health care insurance exceeds 50 percent of the parent’s regular aggregate disposable earnings.

(3)​Accessible to the Child

Health care coverage is presumed accessible if primary care services are covered within 30 miles or 30 minutes from any of a child’s residences. Coverage may be considered at greater times and distances in areas where residents normally travel longer to access primary care services.

3.05(B)​Responsibility to Insure

(1)​When ordering child support, the court must order one of the parents to maintain health care coverage that is accessible to the children and available to the parent at a reasonable cost. MCL 552.605a(2) requires the presumptive use of this manual to determine whether coverage is accessible and available at a reasonable cost, and also permits the court to exercise discretion when ordering coverage.

(a)​To prevent duplicate coverage, extra costs, and avoid unnecessary enforcement actions, only one parent should be ordered to maintain coverage.

(b)​The court should avoid routinely requiring both parties to provide coverage. MCL 552.605a(2) allows ordering both parents to maintain coverage when both parents already provide coverage or both agree to provide coverage.

(2)​Many factors may be used to determine which parent should maintain employer, group, individual, or public coverage for their children. When comparing plans, consider factors like: the accessibility and comprehensiveness of covered services, likely continuation of coverage, affordability of deductibles and co-payments, and reasonableness of the premiums. (The supplement to this manual contains a guide to determine which parent should be ordered to maintain health care coverage. 2025 MCSF-S 3.02.)

(3)​The court may permit a parent to provide required coverage through alternative means, such as a spouse’s or other household member’s coverage or coverage provided by a nonparent-custodian (§4.01(D)(6)), provided that a parent is required to purchase coverage immediately should the alternative coverage stop.

3.05(C)​ Health Care Premium Allocation

(1)​The children’s net determinable portion of health insurance premiums paid by the parents to cover the children should be apportioned according to each parent’s percentage share of family income. §3.01(B)(2).

(a)​The difference between the parents’ shares of the net determinable amounts should be included (as an addition or subtraction) as part of the support payment.

(b)​Adjust base support by adding the net health care premium attributable to the children (whether positive or negative) to the base support obligation after applying the parental time offset formula.

(c)​If the parent provides insurance for the children-in-common using a spouse’s or household member’s benefits, consider amounts paid by the parent’s household as the parent’s premiums paid to insure the children.

(2)​Subject to §4.01(D)(5), allocate the children’s net health care premiums for parent-provided insurance between the parents according to the following steps.

(a)​Determine each parent’s monthly net health care premium attributable to the children by dividing the net premium (actual cost to the parent after subtracting any tax credits, subsidies, other reimbursements, and amount deducted for self-coverage under §2.07(F) by the number of individuals covered and multiply by the number of children covered in this case.

(b)​Prorate each parent’s monthly health care premium attributable to the children by multiplying it and the other parent’s percentage of family income.

(c)​Offset the prorated premiums attributable to the children by subtracting the support recipient’s share of the support payer’s premium from the payer’s share of the recipient’s premium, and round to the nearest cent. (Note: A positive net result means an additional amount must be paid to cover the payer’s share of the support recipient’s premium, while a negative result means a reduction in base support to offset the support recipient’s share of the payer’s premium).

3.06​Child Care Support Obligations

3.06(A)​Subject to §3.01(B), based on each parent’s percentage share of family income, allocate the actual child care expenses for the children in the case under consideration which allow a parent or nonparent-custodian to look for employment, retain employment, or to attend an educational program to improve employment opportunities.

(1)​When custodians or parents have an established child care pattern and can verify that they have actual, predictable and reasonable child care expenses, use the actual costs in the calculation.

(2)​When no established pattern of child care expenses exists, base the expenses on estimates of the community’s average child care costs or several written quotations from local child care providers.

(3)​In calculating child care expenses, presume that the court’s orders for specific parenting time and custody will be followed. However, if a child care provider requires payment to retain a slot for a child without regard to whether the child actually attends, include those additional costs.

3.06(B)​Figure the actual cost of child care by deducting any child care subsidies, credits (including federal tax credit), or similar public or private reimbursements from the gross cost of child care.

3.06(C)​The support payer’s net portion of the actual child care expenses should be ordered paid as a monthly child care support obligation. The support recipient’s share of child care expenses is directly contributed by the support recipient as expenses occur. Allocate net child care costs according to the following steps.

(1)​Determine each individual’s actual monthly child care.

(a)​Calculate each individual’s gross annual child care expenditures.

(b)​Figure the actual cost by deducting any child care subsidies, credits (including tax credits), or reimbursements from the gross cost of child care and convert to a monthly amount.

(2)​Allocate the actual monthly costs by multiplying by the other parent’s percentage share of family income. §3.01(B)(2).

(3)​Offset the two prorated amounts by subtracting the other parent’s share of the support payer's monthly costs from the payer’s share of the other parent’s monthly costs.

3.06(D)​Presume that the need for child care continues until the last day of the month the child is under the age of 13, and unless otherwise stated in the order the total child care reduces by the child’s pro rata share upon that date. At the court’s discretion, the child care support obligation may continue beyond that date as a child’s health or safety needs require.

3.06(E)​Since child care support obligations accrue based on the assumed continuation of the net expenses used to set the currently effective order, custodians and parents need to notify each other of changes in costs, and must notify the friend of the court when they stop incurring child care expenses for a child.

3.06(F)​When parents or custodians do not have an established pattern of child care expenses, the court can order a reasonable amount for future child care expenses conditioned upon the support recipient providing to the other parent and the friend of the court: (1) proof of the recipient’s employment or enrollment in a qualifying educational or training program; (2) proof of the recipient's actual out-of-pocket child care expenses; (3) a written request to the friend of the court asking for implementation of the conditional child care provision; and (4) proof that the support payer was provided copies of items (1)-(3).

3.07​Dependent Benefit Credit

3.07(A)​Credit government insurance program retirement, survivor’s, or disability benefits that were counted as the support payer’s income under §2.01(I) or §2.01(K) against the payer’s support obligation as follows:

(1)​Determine the total child support obligation.

(2)​Subtract the monthly benefit amount that the recipient receives for the children and that is attributable to the payer from the total child support obligation owed by the payer.

(a)​If the children’s payer-based benefit exceeds the total support amount, then no additional support amount should be ordered.

(b)​If the children’s payer-based benefits are less than the payer’s total support amount, then the difference between the benefits received for the children and the total support amount becomes the ordered obligation.

(3)​Under federal law, the administering agency, like the Social Security Administration, holds the sole authority to designate the person who controls the benefits for a minor child (representative payee), therefore, a State’s legal processes cannot be used to alienate federal benefits from a child’s representative payee. A court should not use a child support order to transfer the children’s benefits from a representative payee to a parent or another individual. Payer-based benefits that exceed the total child support obligation owed must remain under the control of the representative payee.

(4)​Because each parent has an individual obligation to provide for that parent’s children, benefits based on another person’s earnings record cannot be credited against or used to satisfy the payer’s support obligation except as permitted under §2.01(K).

3.07(B)​The following cases discuss how Social Security benefits affect support obligations: Frens v Frens, 191 Mich App 654 (1990); Jenerou v Jenerou, 200 Mich App 265 (1993); Paulson v Paulson, 254 Mich App 568 (2002); and Fisher v Fisher, 276 Mich App 424 (2007).

3.07(C)​The supplement to this manual contains additional information and examples on crediting government insurance program dependent benefits. 2025 MCSF-S 3.05.