Montana Child Support Calculator (2026)
Montana calculates child support under guideline-formula guidelines (Admin. R. Mont. 37.62.101–37.62.148 (adopted under § 40-5-209, MCA)). Estimate the guideline amount below.
Montana's guideline formula needs more than a dozen inputs (tax filing status, timeshare percentage, deductions) — a two-field shortcut would mislead you. The state's official calculator implements the full formula:
Open the official Montana calculator →Your Case Details
Answer a few questions to see your estimated range.
Approximate gap between higher-earner and lower-earner.
Estimated Monthly Support
$840 — $1,560
State formulas vary significantly. This estimate uses national averages — your state's guidelines may produce a different number.
Editorially Reviewed — Content reviewed for accuracy using published legal research, government data, and verified court records. See our methodology
Reviewed by Leonard Goldberg, Editor · Last updated
Montana calculates child support with the multi-step Melson formula rather than a simple lookup table (Admin. R. Mont. 37.62.101–37.62.148 (adopted under § 40-5-209, MCA)): each parent first keeps a self-support allowance, the children's primary needs are covered next, and a standard-of-living percentage applies to remaining income. Use the official calculator or worksheet linked above for your figure; this page explains each step.
How Montana Calculates Child Support
Montana uses the Melson Formula (Admin. R. Mont. 37.62.101–37.62.148, adopted under § 40-5-209, MCA), under which each parent first keeps a poverty-based Personal Allowance for self-support ($20,748/year in the 2026 table, 1.3 × the one-person federal poverty guideline) before any support is figured. The remainder funds a fixed Primary Child Support Allowance for the child's basic needs — set only by number of children, not a sliding income-shares schedule — split between the parents in proportion to each one's share of combined available income (Worksheet A). Any income left over is then run through a Standard of Living Adjustment (SOLA): a fixed percentage (0.14 for one child up to 0.47 for eight or more) applied to that residual, with no upper income ceiling. CSSD republishes the tables annually (current version effective February 1, 2026); the formula rules undergo a quadrennial review, most recently completed December 2024, next due December 2028.
Statutory basis: Admin. R. Mont. 37.62.101–37.62.148 (adopted under § 40-5-209, MCA). Exact figure: official Montana calculator.
Worked Example
Two parents, 2 children, using the 2026 CSSD tables. Mother's annual income after allowable deductions is $38,000; Father's is $58,000. Each subtracts the 2026 Personal Allowance of $20,748, leaving 'income available for support' of $17,252 (Mother) and $37,252 (Father) — combined $54,504. Parental shares: Mother 31.65%, Father 68.35%. The 2026 Primary Child Support Allowance for 2 children is $10,374/year, split by parental share: Mother $3,283, Father $7,091. Subtracting each parent's share leaves 'income available for SOLA' of $13,969 (Mother) and $30,161 (Father); applying the 2-child SOLA factor of 0.21 adds $2,933 (Mother) and $6,334 (Father). Total calculated obligation: Mother $6,216/year, Father $13,425/year. Because the children reside primarily with Mother (Father has 110 or fewer overnights/year), the annual transfer equals Father's total obligation of $13,425 ÷ 12 — Father pays Mother $1,119/month (ARM 37.62.134(2)(a)(ii)).
When Courts Deviate From the Guideline
- Financial resources of the child
- Financial resources of both parents
- The standard of living the child would have enjoyed had the parents remained together
- Physical and emotional condition of the child, and the child's educational and medical needs
- Cost of day care for the child
- The parenting plan/residential schedule ordered for the child
- Needs of any other person either parent is legally obligated to support
Frequently Asked Questions
Is there a cap on income considered under Montana's child support guidelines?
No. Unlike states with a hard statutory income cap, Montana's Melson formula applies the Standard of Living Adjustment (SOLA) percentage to all residual income above the Personal Allowance and the parent's share of the Primary Child Support Allowance, with no upper limit — support keeps scaling with income. A court can still deviate for very high or unusual incomes under ARM 37.62.102 and § 40-4-204(2), MCA.
What counts as income under Montana's Melson formula?
ARM 37.62.105 defines 'actual income' broadly: wages, salaries, commissions, self-employment net earnings, pensions, Social Security, unemployment and workers' compensation benefits, capital gains net of losses, dividends, trust income, alimony received, and the value of noncash/in-kind benefits. Excluded are means-tested benefits (SSI, SNAP, TANF, means-tested veterans' benefits) and the income of a new spouse or domestic associate.
How does shared or split parenting time affect the calculation?
Under ARM 37.62.124, a child is treated as residing primarily with one parent — with no separate day-based adjustment — unless the other parent has more than 110 overnights per year with that child. Once that threshold is crossed, or children are split between households, Worksheet B calculates each child's support separately by parent, and the two obligations are offset (ARM 37.62.134(2)(b)) to produce a single net transfer payment.
When does child support end in Montana, and does it cover college?
Under § 40-4-208, MCA, support ends at the child's emancipation or high school graduation (if still enrolled), whichever is later, but never beyond the child's 19th birthday, unless the parents agree otherwise. There is no general statutory obligation to fund college. An exception exists for a child with a qualifying disability causing ongoing financial dependence — support can continue indefinitely for orders in effect on or after July 1, 2019.