Montana child support payments are calculated using the Melson Formula under MCA § 40-4-204 and Administrative Rules of Montana (ARM) 37.62.101-148. Montana is one of only three states (along with Delaware and Hawaii) that uses this three-step calculation model. For 2026, the personal allowance is $20,748 per year per parent, and the primary child support allowance is $6,224 per year. A parent earning $5,000 per month with one child and standard parenting time typically pays between $600 and $900 monthly, though exact amounts depend on both parents' incomes, healthcare costs, childcare expenses, and the parenting time arrangement.
Key Facts: Montana Child Support 2026
| Factor | Details |
|---|---|
| Calculation Model | Melson Formula (ARM 37.62.101) |
| Personal Allowance | $20,748/year ($1,729/month) per parent |
| Primary Child Support Allowance | $6,224/year for one child |
| Filing Fee (Dissolution with Children) | $250 ($200 filing + $50 judgment) |
| Modification Filing Fee | $80-$120 |
| Parenting Time Adjustment Threshold | 110 overnights/year |
| Support Termination Age | 18 or high school graduation (max age 19) |
| Modification Threshold | 30% income change or 3-year review |
| Wage Garnishment Limit | 50-65% of disposable income |
| Interest on Arrears | Court discretion (no automatic rate) |
How Montana Calculates Child Support
Montana calculates child support using the Melson Formula, which first deducts a personal self-support allowance of $20,748 per year from each parent's gross income before determining the support obligation. The calculation process under ARM 37.62.105 follows five distinct steps: determining each parent's gross income from all sources, subtracting the personal allowance ($1,729 monthly), combining the remaining available income, cross-referencing the guidelines table to find the basic support obligation, and allocating that obligation proportionally based on each parent's share of combined income.
The Melson Formula differs from the Income Shares model used by most states because it ensures each parent retains enough income to meet their own basic needs before calculating support. This approach reflects Montana's policy that parents cannot support their children if they cannot first support themselves. The personal allowance of $20,748 equals approximately 1.3 times the federal poverty guideline for one person.
Gross Income Sources Under Montana Law
Montana courts include the following income sources when calculating child support under ARM 37.62.103:
- Wages, salaries, commissions, and bonuses from employment
- Self-employment income (gross receipts minus ordinary business expenses)
- Unemployment compensation and workers' compensation benefits
- Social Security benefits, disability payments, and veterans benefits
- Pension and retirement distributions
- Rental income and royalties
- Interest, dividends, and investment returns
- Alimony received from a prior marriage
- Annuity payments and trust income
Allowable Deductions Before Calculation
Before determining the support obligation, Montana allows specific deductions from gross income:
- Federal and Montana state income taxes
- FICA taxes (Social Security at 6.2% and Medicare at 1.45%)
- Mandatory retirement contributions required by employer
- Union dues and required professional fees
- Health insurance premiums for the parent only (children's premiums handled separately)
- Child support paid for children from other relationships
Montana Child Support Guidelines Table 2026
The Montana Child Support Services Division (CSSD) publishes updated guidelines tables effective February 1, 2026. These tables specify the dollar amount parents at each income level would be expected to spend on their children based on economic data about actual child-rearing costs in Montana.
Primary Child Support Allowance by Number of Children
| Number of Children | Annual Allowance | Monthly Equivalent |
|---|---|---|
| 1 child | $6,224 | $519 |
| 2 children | $10,374 | $865 |
| 3 children | $14,523 | $1,210 |
| 4 children | $16,598 | $1,383 |
| 5 children | $18,673 | $1,556 |
| 6 children | $20,748 | $1,729 |
These amounts represent the base support obligation before proportional allocation between parents. The complete guidelines tables are available in CSSD Policy Manual CS 404.2 and cover combined incomes from $0 to over $25,000 monthly.
How Much Is Child Support in Montana: Example Calculations
Understanding how much is child support in Montana requires examining how the Melson Formula applies to real income scenarios. The following examples illustrate typical payment amounts for Montana families in 2026.
Example 1: Standard Custody Arrangement
When the custodial parent earns $3,500 gross monthly ($42,000 annually) and the non-custodial parent earns $5,500 gross monthly ($66,000 annually) with one child and standard parenting time (less than 110 overnights), the calculation proceeds as follows:
- Parent A adjusted income: $3,500 - $1,729 = $1,771
- Parent B adjusted income: $5,500 - $1,729 = $3,771
- Combined available income: $5,542
- Parent B's share: 68% ($3,771 ÷ $5,542)
- Base obligation for one child at this income: approximately $650
- Parent B's monthly payment: approximately $442
Example 2: Shared Parenting Time
Montana's parenting time adjustment activates when the non-custodial parent exercises more than 110 overnights annually with the child. For the same income scenario above with 150 overnights (41% parenting time), the calculation includes a multiplier:
- Parenting time percentage: 150 ÷ 365 = 41.1%
- Adjustment multiplier: 1 - (2 × 0.411) = 0.178
- Adjusted monthly payment: $442 × 0.178 = approximately $79
This significant reduction reflects the economic reality that the non-custodial parent incurs substantial direct expenses during extended parenting time.
Parenting Time Adjustments and the 110-Overnight Threshold
Montana reduces child support obligations when the non-custodial parent exercises more than 110 overnights per year under ARM 37.62.136. This threshold equals approximately 30% of the year and recognizes that extended parenting time creates duplicated household expenses including food, utilities, transportation, and activities. Parents with exactly 110 overnights receive no adjustment, while those with 182.5 overnights (50% parenting time) may see support reduced to near zero.
The adjustment formula is: Final Support = Base Obligation × (1 - 2 × NCP Parenting Time Percentage). For example, a parent with 140 overnights (38.4%) multiplies their base obligation by (1 - 2 × 0.384) = 0.232, reducing support to approximately 23% of the unadjusted amount.
Additional Child Support Components
Beyond the basic support obligation, Montana courts allocate specific expenses proportionally between parents under ARM 37.62.140:
Healthcare Costs
- Health insurance premiums for the child: divided proportionally by income share
- Unreimbursed medical expenses: first $250 per child per year paid by custodial parent, excess divided proportionally
- Dental and vision care: included in unreimbursed medical expenses
- Mental health treatment: divided proportionally when court-ordered or medically necessary
Work-Related Childcare
- Daycare expenses: divided proportionally when required for parent's employment or job training
- Before and after school care: included when necessary for work schedules
- Summer camp and care programs: divided proportionally for work-related needs
Educational Expenses
- Private school tuition: discretionary, may be ordered if historically attended
- Tutoring and special education: divided proportionally when necessary
- Extracurricular activities: discretionary, courts consider historical participation
Child Support Modification in Montana
Montana allows modification of existing child support orders when circumstances change substantially under MCA § 40-4-208. Parents must demonstrate either a substantial change since the last order or wait until three years have passed for an automatic review eligibility. The modification threshold under ARM 37.62.2103 requires at least a 30% increase or decrease in either parent's income to justify modification within the three-year window.
Grounds for Child Support Modification
Montana courts recognize the following as substantial changes warranting modification:
- Income increase or decrease of 30% or more
- Emancipation or death of a child covered by the order
- Child permanently moving from one parent's household to the other
- Development of special needs not considered in the original order
- Change in parenting time crossing the 110-overnight threshold
- Significant change in healthcare or childcare costs
- Disability rendering a parent unable to work
Administrative vs. Court Modification
Parents can request modification through two pathways:
-
CSSD Administrative Review: Available every 36 months automatically, or anytime with evidence of substantial change. Contact CSSD at 1-800-346-5437. No filing fee for IV-D cases.
-
District Court Motion: File in the court that issued the original order. Filing fee of $80-$120 depending on county. Required when parents disagree on modification terms.
Montana courts cannot modify support retroactively before the motion filing date. Parents experiencing income changes should file promptly rather than waiting and accumulating arrears or overpayments.
When Does Child Support End in Montana?
Child support in Montana terminates under MCA § 40-4-208(5) upon the earliest of these events:
- The child turns 18 and has graduated high school or obtained a GED
- The child graduates from high school while still under 19 years old
- The child's 19th birthday regardless of high school enrollment
- Court-ordered emancipation before age 18
- Marriage of the minor child
- Enlistment in active-duty military service
- Death of the child or obligor parent
Disability Exception to Termination
Montana law provides an exception for children with disabilities. Support obligations are not terminated solely based on the child's age when the child has a disability that causes them to be financially dependent on the custodial parent and the custodial parent remains the child's primary caregiver. Parents must petition the court to continue support beyond the standard termination age.
College Support Not Required
Montana does not require parents to pay for college expenses. Unlike some states that extend support through undergraduate education, Montana's obligation ends at age 18 or high school graduation (maximum age 19). Parents may voluntarily agree to college contribution in their settlement agreement, but courts cannot order it absent such agreement.
Child Support Enforcement in Montana
The Montana Child Support Services Division (CSSD) enforces child support orders through multiple mechanisms under MCA Title 40, Chapter 5. The division collected over $140 million annually in child support for Montana families.
Wage Garnishment
Income withholding represents the primary enforcement tool. Montana law permits garnishment of up to 50% of disposable income for current support and arrears combined. When the obligor is not supporting another spouse or children and is 12 or more weeks behind, garnishment can reach 65% of disposable income. Employers must deduct payments after taxes but before voluntary deductions and other garnishments.
Additional Enforcement Tools
- Federal and state tax refund intercepts
- Passport denial for arrears exceeding $2,500
- Driver's license suspension
- Professional and occupational license suspension
- Recreational license suspension (hunting, fishing)
- Credit bureau reporting
- Liens on real and personal property
- Bank account levy
- Contempt of court proceedings with potential jail time
Interest on Arrears
Montana does not automatically apply interest to unpaid child support arrears. Unlike many states that impose 6-12% annual interest, Montana courts determine interest application on a case-by-case basis. However, arrears remain collectible for 10 years after the support obligation terminates under MCA § 40-5-272, and child support debt cannot be discharged through bankruptcy.
Penalties for Non-Payment
Willful failure to pay child support can result in:
- Civil contempt with up to 6 months jail per violation
- Criminal nonsupport charges for persistent non-payment
- Fines up to $500 per contempt finding
- Attorney's fees awarded to the custodial parent
- Negative credit reporting affecting loans and housing
Imputed Income for Unemployed or Underemployed Parents
Montana courts impute income to parents who are voluntarily unemployed or underemployed under ARM 37.62.106. The court presumes all parents are capable of working at least 40 hours per week at minimum wage, absent evidence to the contrary. Montana's minimum wage is $10.55 per hour as of 2026, yielding imputed monthly income of approximately $1,829.
When determining imputed income, courts consider:
- Employment history and job skills
- Educational background and credentials
- Physical and mental health limitations
- Prevailing wages in the local community
- Available job opportunities in the parent's field
- Childcare responsibilities and costs
A parent who quits a job or takes lower-paying employment to reduce child support may have their obligation calculated based on earning capacity rather than actual current income. Courts look unfavorably on strategic underemployment.
How to Apply for Child Support in Montana
Parents can establish child support through the Child Support Services Division or through District Court. The CSSD provides services at no cost for IV-D cases (cases involving public assistance or CSSD services).
Through CSSD
- Complete an application at Montana CSSD
- Provide income documentation for both parents
- Submit birth certificates and paternity information
- CSSD will calculate support using the guidelines
- Administrative order issued within 60-90 days
Through District Court
- File Petition for Dissolution with Children ($250 filing fee) or Petition for Child Support ($120 filing fee)
- Serve the other parent with summons and petition
- Complete financial disclosure forms
- Attend hearing or submit proposed parenting plan
- Court enters support order following guidelines
Frequently Asked Questions
How much is child support in Montana for one child?
Child support in Montana for one child ranges from $300 to $1,200 monthly depending on both parents' incomes and parenting time arrangements. The base primary support allowance is $6,224 per year ($519 monthly), which is then allocated proportionally between parents based on their respective shares of combined income. A non-custodial parent earning $4,000 monthly with a custodial parent earning $3,000 monthly typically pays approximately $350-$450 for one child.
What is the minimum child support in Montana?
Montana has no statutory minimum child support amount, but courts generally will not order less than $50 per month regardless of income. For parents with income below the personal allowance of $20,748 per year ($1,729 monthly), the Melson Formula produces $0 available income for support calculation. However, courts may impute minimum wage income ($1,829 monthly) to voluntarily unemployed parents, resulting in a minimum obligation of approximately $150-$200 monthly for one child.
How long does child support last in Montana?
Child support in Montana lasts until the child turns 18 and graduates high school, or until the child's 19th birthday, whichever occurs first under MCA § 40-4-208(5). If a child graduates high school at age 17, support continues until the child turns 18. Montana does not extend support for college attendance. Children with qualifying disabilities may receive support beyond age 19 if they remain financially dependent on the custodial parent.
Can child support be modified in Montana?
Yes, Montana permits child support modification when there has been a substantial change in circumstances under ARM 37.62.2103. The threshold requires at least a 30% change in either parent's income, or parents may request automatic review after 36 months. Other qualifying changes include a child moving between households, crossing the 110-overnight parenting time threshold, or a child's development of special needs. Modifications cannot be applied retroactively before the filing date.
Does Montana consider the new spouse's income for child support?
No, Montana does not include a new spouse's income in child support calculations. Only the biological or adoptive parents' incomes count toward the support obligation under ARM 37.62.105. However, if a new spouse's income reduces a parent's living expenses, the court may consider this indirectly when evaluating lifestyle and ability to pay. Remarriage alone does not justify modification of existing support orders.
How is child support collected in Montana?
Montana collects child support primarily through automatic wage withholding, where employers deduct payments directly from paychecks and remit them to CSSD for distribution. Additional collection methods include tax refund intercepts (federal and state), bank account levies, property liens, and license suspensions. CSSD can garnish up to 50% of disposable income for current support and arrears, increasing to 65% when the obligor is 12 or more weeks behind and not supporting other dependents.
What happens if I don't pay child support in Montana?
Failure to pay child support in Montana triggers escalating enforcement actions including wage garnishment up to 65% of income, tax refund interception, passport denial for arrears over $2,500, driver's license suspension, professional license suspension, and credit reporting. Persistent non-payment can result in contempt of court with jail sentences up to 6 months per violation. Arrears remain collectible for 10 years after the obligation ends and cannot be discharged in bankruptcy.
Can I represent myself in a Montana child support case?
Yes, Montana permits self-representation (pro se) in child support cases. The Montana Judicial Branch provides free forms and instructions for child support matters at courts.mt.gov. The Child Support Services Division also assists parents in establishing and enforcing support orders at no cost for qualifying cases. However, complex cases involving high incomes, business ownership, or disputed parenting time benefit from attorney representation.
How does shared custody affect child support in Montana?
Shared custody in Montana reduces child support when the non-custodial parent has more than 110 overnights per year under ARM 37.62.136. The adjustment formula multiplies the base obligation by (1 - 2 × parenting time percentage). For equal 50/50 custody (182.5 overnights each), support approaches $0 because both parents provide direct care half the time. Parents with 140 overnights (38%) see support reduced to approximately 23% of the unadjusted amount.
Where do I file for child support in Montana?
File for child support in the District Court of the county where either parent resides in Montana. Montana has 56 counties, each with a Clerk of District Court office. The filing fee is $250 for dissolution cases with children or $120 for standalone parenting actions. Alternatively, apply through the Child Support Services Division online at dphhs.mt.gov/cssd for no-cost establishment services in qualifying cases.