Montana Child Support — Calculator, Laws & Guide (2026)

Understanding Montana child support laws helps both custodial and non-custodial parents know their rights and obligations. This comprehensive Montana child support guide covers how payments are calculated, what income counts, when support can be modified, and how orders are enforced. Whether you are going through a divorce, seeking a modification, or dealing with non-payment, this guide explains Montana’s child support system in plain language.

Verified against Montana statutes and federal OCSE guidelines as of April 2026.

Montana Child Support Overview

Montana uses the income shares model for calculating child support. This model is based on the principle that children should receive the same proportion of parental income they would have received if the family were intact. Both parents’ incomes are combined, and the support obligation is divided proportionally.

Both parents’ incomes are combined to determine total income available for child support. Each parent’s income is divided by the total to determine their proportional share of the primary child support allowance. The formula includes a self-support reserve set at 130% of the federal poverty level, a primary child support allowance based on combined parental income and number of children, supplements for healthcare and childcare, and a Standard of Living Adjustment (SOLA) that allocates additional income above basic needs. Guidelines tables are updated annually (current tables effective February 1, 2026).

How Montana Calculates Child Support

The Montana child support calculation considers multiple factors:

1. Determine each parent’s gross income — wages, salary, commissions, bonuses, self-employment income, investment income, and other sources.
2. Calculate combined parental income — add both parents’ adjusted gross incomes together.
3. Apply the guideline schedule — Montana’s guidelines provide a base support amount based on combined income and number of children.
4. Prorate between parents — each parent’s share is proportional to their percentage of the combined income.
5. Add healthcare and childcare costs — these are added to the base amount and divided proportionally.
6. Apply adjustments — parenting time credits, other child obligations, and special circumstances may adjust the final amount.

Online calculator: Use our child support estimator below to calculate your estimated obligation.

What Counts as Income in Montana

Gross income defined as “economic benefit from whatever source derived.” Includes: salaries, wages, tips, commissions, bonuses, earnings, profits, dividends, severance pay, pensions, periodic distributions from retirement plans, draws or advances against wages or salaries, interest, trust income, annuities, royalties, alimony or spousal maintenance, Social Security benefits, veterans benefits, workers compensation benefits, unemployment benefits, disability payments, earned income credit, and other government payments and benefits. Capital gains (net of losses) are included and may be averaged over 3+ years if recurring. Excludes: income of subsequent spouses or household members, means-tested public assistance (TANF), and lump-sum Social Security or disability benefits received by the child. Allowable deductions from gross income include extraordinary unreimbursed medical expenses needed to maintain a parent’s earning capacity and current annual interest on student loans.

Imputed income: YES. Montana presumes all parents are capable of working at least 40 hours per week at minimum wage, absent evidence to the contrary. Imputation considers: existing job opportunities and earning levels in the community, the parent’s age, literacy, health, criminal record, record of seeking work, and other employment barriers. Income is NOT imputed if a parent has made diligent efforts to find and accept suitable work or return to customary self-employment without success.

Deviation factors: The guidelines amount is a rebuttable presumption under ARM 37.62.102. A variance may be granted upon consideration of factors in MCA 40-4-204, 40-4-208, and 40-6-116 at the request of either party. Any variance must account for the best interests of the child. Specific triggers for review include: special needs developed by a child, movement of a child from one parent’s home to another, and orders that were set without reference to the guidelines.

Healthcare & Childcare in Montana Child Support

Health insurance: Every Montana child support order must include a provision for medical support, typically requiring health insurance coverage. When a parent can provide reasonable-cost employer-based health insurance, they may be required to do so. The cost of adding children to an existing insurance policy (or cost of a child-only policy) is added as a supplement to the primary child support allowance under ARM 37.62.123. Unreimbursed healthcare expenses exceeding 250 per child per year that are recurring and predictable are also added as a supplement. These supplemental costs are split proportionally between parents based on their respective income shares.

Childcare costs: Reasonable childcare costs incurred by a parent as a prerequisite to employment are added as a supplement to the primary child support allowance under ARM 37.62.123. The total supplemental childcare costs are divided proportionally between parents according to their parental share of income as determined under ARM 37.62.118.

When Does Montana Child Support End?

In Montana, child support generally ends when the child reaches Child support terminates at age 18 OR upon graduation from high school if the child is still enrolled, whichever is LATER — but in no event later than the child’s 19th birthday. Support may terminate earlier by court-ordered emancipation. Exception: support does NOT terminate based solely on age if the child has a disability causing financial dependence on the custodial parent and the custodial parent is the child’s primary caregiver — support continues until the court finds the individual is no longer disabled or no longer financially dependent. Support does not terminate upon the death of the obligor parent; it may be modified, revoked, or commuted to a lump sum. (MCA 40-4-208). However, support may continue or end earlier based on:

• The child graduates from high school (if still a minor)
• The child becomes emancipated (marriage, military service, self-supporting)
• The child has special needs requiring ongoing support
• College support: NO. Montana does not require parents to contribute to college or post-secondary education costs. Support cannot be extended beyond age 19 for college expenses unless both parents agree in writing or the divorce decree contains an express provision requiring post-secondary education support.

Modifying Montana Child Support

When to modify: A review is available when there is an increase or decrease of at least 30% in a parent’s income for child support; adoption, emancipation, or death of a child; movement of a child from one parent’s home to another; development of special needs by a child; or evidence that the original order was set without reference to the child support guidelines. Generally, modification cannot be requested within 12 months of establishment or most recent modification, with exceptions for medical support order violations. (ARM 37.62.2103)

How to modify: Either parent may request a review through the Child Support Services Division (CSSD) of DPHHS or through district court. CSSD calculates the new support obligation using the Montana Child Support Guidelines and serves notice on both parents. If both parents consent, the modification proceeds. If either parent disagrees, a hearing may be requested before an administrative law judge (ALJ) who determines the support amount. Modifications are retroactive to the date the request was filed but not earlier.

Either parent can request a modification. Changes are typically not retroactive to before the date of filing the modification request.

Montana Child Support Enforcement

Montana has multiple tools to enforce child support orders when a parent fails to pay:

• Income withholding (wage garnishment — primary method)
• federal and state tax refund intercept
• property liens (real estate
• vehicles)
• driver’s license suspension
• professional license suspension
• recreational license suspension
• passport denial (arrears exceeding 2500)
• contempt of court proceedings (fines or jail)
• credit bureau reporting. The CSSD also works with the Federal Parent Locator Service to find noncustodial parents.

Contact Child Support Services Division (CSSD), Montana Department of Public Health and Human Services (DPHHS) at https://dphhs.mt.gov/cssd/ for enforcement assistance.

Additional Montana rules: Montana is one of only three states (along with Delaware and Hawaii) using a Melson-based formula rather than the standard income shares model. The Montana version includes a Standard of Living Adjustment (SOLA) that allocates additional income above basic needs back to the child, calculated by subtracting each parent’s share of primary child support allowance and supplements from income available for support. Montana does NOT charge interest on unpaid child support arrears — unusual among states. The self-support reserve is set at 130% of the federal poverty level. Guidelines tables are republished annually by CSSD as soon as practical after release of underlying data. Support does not terminate upon the death of the obligor parent.

Official Sources & Resources

• Child Support Services Division (CSSD), Montana Department of Public Health and Human Services (DPHHS): https://dphhs.mt.gov/cssd/
• Federal OCSE: acf.hhs.gov/css
• Cornell LII — Child Support: law.cornell.edu
• Montana Guidelines Statute: MCA 40-5-209 (implementing statute requiring child support guidelines); MCA 40-4-204 (support provisions in dissolution); MCA 40-4-208 (modification and termination); Administrative Rules of Montana (ARM) Title 37, Chapter 62, Subchapter 1 (ARM 37.62.101 through 37.62.148) — these contain the detailed guidelines, income definitions, calculation rules, and tables.

Last verified April 2026. Contact us if you notice outdated information.

Estimate Your Child Support

Use our free child support estimator to calculate estimated monthly payments. Enter both parents’ incomes, number of children, and custody arrangement to see a personalized breakdown based on your state’s formula.

Related Guides

• Montana Divorce Process Guide
• Montana Child Custody Guide
• Montana Alimony Guide
• All Child Support Guides