How it works · official guideline
How child support is calculated in Montana
Montana’s guidelines (ARM 37.62.101–148, adopted by the Child Support Services Division under MCA 40-5-209) subtract a personal allowance from each parent’s income, share the children’s primary and supplemental needs in proportion to income, and then add a standard of living adjustment from income left over. Courts must use the guidelines, and the result is presumed correct unless shown by clear and convincing evidence to be unjust.[1]
Key facts: child support in Montana
| Guideline model | Melson formula[1] |
|---|---|
| Low income | Personal allowance: $20,748 per year for each parent (effective Feb. 1, 2026)[2] |
| Percentages | Primary child support allowance: $6,224 per year for one child (2026)[2] |
| Percentages | Standard of living adjustment multipliers: .14 (1 child), .21 (2), .27 (3), .31 (4) … .47 (8+)[3] |
| Official worksheet | Montana Child Support Guidelines Worksheets (A–E) & Instructions |
| Guideline last checked | October 26, 2026 |
Montana’s model
Melson formula
Melson-type formula: personal allowance for each parent, primary child allowance shared by income, plus a standard of living adjustment.
Official worksheet · Montana Department of Public Health and Human Services, Child Support Services Division
Montana Child Support Guidelines Worksheets (A–E) & InstructionsLink checked October 26, 2026
Why no calculator here? We publish a calculator only after it reproduces the state’s official numbers exactly. We haven’t matched Montana’s yet, so use the official worksheet for a number.
From the official text
The rules behind Montana’s numbers
The guideline is MCA 40-4-204(3)(a). Open each rule to read the exact words.
- Low income
Personal allowance: $20,748 per year for each parent (effective Feb. 1, 2026)
Each parent keeps a personal allowance before income counts toward support; CSSD updates it each year from the federal poverty guidelines.[2]
Official text · CSSD Policy CS 404.2, Montana Child Support Guidelines Tables
“Table 1 --Personal Allowance per Year for Each Parent: $20,748”
- Percentages
Primary child support allowance: $6,224 per year for one child (2026)
The children’s primary allowance starts at $6,224 a year for one child and rises with more children ($10,374 for two, $14,523 for three).[2]
Official text · CSSD Policy CS 404.2
“Table 2 --Primary Child Support Allowance Per Year: $6,224”
- Percentages
Standard of living adjustment multipliers: .14 (1 child), .21 (2), .27 (3), .31 (4) … .47 (8+)
Income remaining after allowances is multiplied by a standard-of-living (SOLA) factor that rises with the number of children.[3]
Official text · Montana Child Support Guidelines Worksheets (A–E) & Instructions, Worksheet E
“1 $ [ ] x .14”
- Minimum order
Minimum contribution: 12% of income after deductions (when income exceeds the personal allowance)
A parent qualifies for a minimum contribution instead of a full proportional share in some low-income situations; when income after deductions is above the personal allowance, the minimum contribution is 12% of income after deductions.[4]
Official text · CSSD Policy CS 404.1, Child Support Guidelines
“In this case the minimum contribution is 12% of Income after Deductions.”
- Shared parenting time
Combination parenting: more than 110 days a year with each parent
A combination-parenting calculation applies when a child spends more than 110 days a year with each parent (or in certain split arrangements).[4]
Official text · CSSD Policy CS 404.1
“Any of the children spend more than 110 days with one parent, and more than 110 days with the other parent.”
- Departing from the guideline
Guideline amount presumed; rebutted only by clear and convincing evidence
The guideline amount is presumed adequate unless the court finds by clear and convincing evidence that it is unjust or inappropriate, and the court must state its reasons.[1]
Official text · MCA 40-4-204(3)(a)
“The amount determined under the guidelines is presumed to be an adequate and reasonable support award, unless the court finds by clear and convincing evidence that the application of the standards and guidelines is unjust to the child or to any of the parties or that it is inappropriate in that particular case.”
Guideline: MCA 40-4-204(3)(a) (Montana Legislature), checked October 26, 2026.
Estimate and general information only — not legal advice. MediationList is a directory, not a law firm, and doesn’t endorse any mediator. Guidelines change; confirm with the official worksheet (sources checked October 26, 2026). See also divorce laws in Montana and child support in every state.
Sources
Montana’s child support guideline, rules and official tools, read on the official sites, with the date we checked each.