Montana Child Support Calculator

Montana uses the Melson formula, a more complex variation of income shares that first reserves a self-support amount for each parent, then allocates income to the children's primary needs, and adds a standard-of-living adjustment. The guideline is set by Mont. Code Ann. § 40-4-204; Admin. R. Mont. 37.62.101 et seq..

No — this is a guideline estimate. Courts start from the guideline amount but can deviate for factors like extraordinary medical costs, special needs, other support obligations, or agreements between parents. For an official figure, consult your court’s self-help center or a family law attorney.

In most states, including under most guideline models, substantial parenting time (often above roughly 20–30% of overnights) reduces the paying parent's obligation. Our calculator applies a simplified parenting-time adjustment; Montana's courts apply their own specific rules, so treat shared-custody results as rough estimates.

Generally all income: wages, self-employment, bonuses, commissions, and often investment income. Montana's guideline applies to net (after-tax) income — our calculator approximates net income from the gross figures you enter. Courts may also impute income to a parent who is voluntarily unemployed or underemployed.