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Montana Child Support

Melson Formulamodel estimate

Estimate for Montana

Montana uses the Melson Formula model.

⚠ Model estimate — not yet verified. MODEL ESTIMATE. Simplified Melson (self-support reserve + primary support). Montana applies additional standard-of-living adjustments. Verify with the official guideline.

Enter the paying parent’s net (after-tax/deductions) monthly income.

Estimated monthly support$1,058.64per month
Annual estimate$12,703.68
Effective rate21.2%
MethodMelson Formula: self-support reserve + primary support, split by adjusted income
View calculation breakdown
Self-support reserve (each parent)$1,729
POVC reserve (each parent)$865
Obligor adjusted income$2,406
Primary support pool (30% of adjusted)$1,144
Obligor primary support$722
Standard-of-living adjustment (obligor share)336.84%
Estimated monthly support$1,059

Estimated monthly support by number of children

$1,2111$1,0592$9073$8314$7555$1,4396+
At the incomes you entered, for 2 children.

§ How Montana calculates support

Montana uses the Modified Melson Formula (ARM 37.62), one of three U.S. states. Each parent keeps a personal (self-support) allowance of $20,748/year (~$1,729/month, 1.3x the one-person poverty line), the child's primary support allowance is funded (30% of the personal allowance for one child, scaling with more children), and a Standard of Living Adjustment (SOLA) of 14%/21%/27%/31%/35% shares remaining income. Deviation requires clear-and-convincing evidence.

Content verified against official sources on 2026-08-09.

✦ How to open or modify a case in Montana

  1. Determine each parent's gross monthly income from all sources.
  2. Subtract taxes, FICA, and allowed deductions to get net available income.
  3. Subtract each parent's personal allowance ($1,729/month eff. 2/2026).
  4. Combine remaining income and compute the primary child support allowance (e.g., $519/mo for 1 child), split by income share.
  5. Apply the SOLA percentage (14% for 1 child, up to 35% for 5+) to income left after the allowance and primary support.
  6. Add the child's health insurance and childcare; allocate by income share using Form CS 404.2.

◈ Illustrative examples

Illustrative example
Illustrative example - Melson, 1 child

Scenario: Parent A gross $5,000, Parent B gross $3,000; personal allowance $1,729 each. A available = $3,271, B = $1,271; combined $4,542.

Walk-through: Primary allowance $518.67/mo: A 72% = $373.44, B 28% = $145.23. SOLA income = $4,542 - $518.67 = $4,023.33; 14% = $563.27 split 72/28 = $405.55 / $157.72. Noncustodial B total ~$303/month plus add-ons.

Takeaway: Montana's formula protects parental subsistence first, then the child's primary need, then shares prosperity via SOLA.

? Frequently asked questions

When does Montana support end?
At 18, or high-school graduation (not past 19). College is not required by a Montana court.
How is the personal allowance set?
It equals 1.3x the federal poverty guideline for a one-person household and is updated every year (e.g., $20,748 for 2026).

↗ Official policy & agency links

Montana DPHHS - Child Support Services ↗Montana Administrative Rules (ARM 37.62) ↗

Sources verified: https://rules.mt.gov/ · https://dphhs.mt.gov/cssd · https://recordinglaw.com/us-laws/united-states-child-support-laws/montana-child-support-laws/ · https://observed.org/child-support-guidelines-in-montana

Statute: Mont. Code Ann. § 40-4-204Income basis: netData last updated: 2026-08-08Next review: 2027-01-01Status: estimate pending verification

How Montana calculates support

Montana uses the Melson Formula.

Not legal or financial advice. This estimate follows the state’s statutory guideline formula but cannot capture every factor a court considers (health insurance, childcare, prior orders, deviations, imputed income).