Montana Child Support Calculator

How Montana Calculates Child Support

Montana determines child support using the Melson Formula, the standard set out in ARM ch. 37.62 / CS 404.2 Tables. The Melson Formula is a three-step approach that first sets aside a basic self-support reserve for each parent, then covers the children's primary needs, and finally adds a share of any remaining income so the children benefit from their parents' higher earnings.

The calculator above applies that formula to the income and expense figures you enter and shows each step of the math, so you can see exactly how the estimate is built. Because every order ultimately runs through a judge, the guideline figure is a starting point rather than a guaranteed result — the sections below explain what goes into it and where real orders can differ.

Key Rules Behind the Montana Formula

• Montana uses a modified Melson-style formula under ARM chapter 37.62, worked through Worksheets A-E — not the income-shares schedule model most states use.
• Each parent first keeps a personal allowance of $20,748 per year ($1,729/month, CS 404.2 Table 1) before any income is considered available for support.
• The children's primary allowance comes from a per-family table ($6,224/year for one child up to $20,748/year for six, CS 404.2 Table 2), plus health insurance and childcare supplements, shared in proportion to each parent's available income.
• A standard of living adjustment (SOLA) then adds 14% (one child) to 39% (six children) of a parent's remaining income above the allowance, so children share in a parent's higher earnings.
• A minimum-obligation floor applies even at low incomes: 12% of income after deductions, or the Worksheet C income-ratio amount when income falls below the personal allowance.
• When the children spend more than 110 days per year with the paying parent, a parenting-time credit of 0.69% per additional day applies (ARM 37.62.134). Montana computes this per child on Worksheet B and nets the parents' obligations; this calculator applies it to the total, which is a simplification.
• The guideline amount is a rebuttable presumption — courts may vary it with written findings under ARM 37.62.102.

What Counts as Income

Child support guidelines are built on each parent's income, so the figure you enter matters more than any other input. Most states start from a broad definition of gross income that includes wages, salary, tips, commissions, bonuses, self-employment earnings, and many forms of government benefits, then subtract specific deductions to reach the income the formula actually uses.

Montana's rules under ARM ch. 37.62 / CS 404.2 Tables spell out which deductions apply and whether the formula runs on gross or net income. The calculator's field labels tell you which figure to enter; when in doubt, use your most recent pay stubs and tax return, and confirm the details in the Montana child support laws guide.

How to Establish a Child Support Order in Montana

A child support obligation becomes enforceable only once a court or the state child support agency issues an order. Either parent can request one, and in Montana, as in every state, the local child support agency that operates under the federal Title IV-D program can open a case, locate the other parent, establish paternity if needed, and ask the court to set support using the guideline formula.

When you apply, expect to provide proof of income for both parents, the child's information, and details about health insurance and childcare costs — the same inputs this calculator uses. Running your numbers here first gives you a realistic idea of the order amount before you file.