Montana Child Support
Calculator (2026)
Montana uses the ARM Title 37, chapter 62 worksheet (CSSD bulletin CS 404.2, eff. Feb 1, 2026): personal allowance $20,748/yr per parent (1.3× FPG), primary child support allowance allocated by income share, SOLA 14-47% for 1-8 children, 110-day parenting-day threshold with per-day allocation and offset (ARM 37.62.134), tiered minimum obligations (ARM 37.62.126).
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How Child Support Is Calculated in Montana
Montana calculates child support using the Melson-variant worksheet (one of only 3 Melson states) established under MCA §40-4-204; ARM Title 37, ch. 62. This is a statutory formula that leaves limited room for judicial discretion on the base calculation amount, ensuring consistency and predictability for families across the state.
The Formula
Per-parent income after taxes − personal allowance → primary allowance by income share + SOLA → parenting-day offset.
The calculation begins with determining each parent's net disposable income, which includes virtually all sources of income minus taxes, mandatory payroll deductions, and certain hardship deductions. The court then applies the statutory formula using the time each parent has primary physical responsibility for the children and the applicable income allocation brackets.
Beyond the base formula amount, Montanarequires additional contributions for mandatory add-on expenses. These typically include childcare costs necessary for the custodial parent's employment or education, uninsured healthcare expenses for the children, and in some cases, educational and travel costs. These add-ons are split between parents in proportion to their respective incomes.
Primary statute: MCA §40-4-204; ARM Title 37, ch. 62
Key Child Support Rules in Montana
Melson-variant worksheet (with Delaware and Hawaii).
Personal allowance $20,748/yr per parent (CS 404.2, eff. 2/1/2026).
Primary allowance $6,224-$24,897/yr for 1-8 children; SOLA 14-47%.
110-day parenting threshold, then per-day allocation + offset (ARM 37.62.134).
Minimum obligation: 12% of income after deductions (ARM 37.62.126).
What Makes Montana Child Support Unique
Melson-variant worksheet — unique to 3 states.
Constants republished annually by CSSD.
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Montana Divorce Procedure at a Glance
Residency Requirement
90-day domicile (MCA §40-4-104); District Court
Mandatory Waiting Period
Decree no earlier than 21 days after service (§40-4-105(3))
No-Fault Ground
Irretrievably broken (MCA §40-4-104)
State Income Tax
Two brackets (HB 337, 2025): 4.7% ≤$47,500 single / 5.65% above (top drops to 5.4% in 2027).
In-Depth Montana Divorce Guides
More Montana Divorce Calculators
Frequently Asked Questions About Montana Child Support
How is child support calculated in Montana?
Montana uses the Melson-variant worksheet (one of only 3 Melson states) under MCA §40-4-204; ARM Title 37, ch. 62. Montana uses the ARM Title 37, chapter 62 worksheet (CSSD bulletin CS 404.2, eff. Feb 1, 2026): personal allowance $20,748/yr per parent (1.3× FPG), primary child support allowance allocated by income share, SOLA 14-47% for 1-8 children, 110-day parenting-day threshold with per-day allocation and offset (ARM 37.62.134), tiered minimum obligations (ARM 37.62.126).
What factors affect Montana child support amounts?
Key factors include both parents' income, the number of children, custodial time share, mandatory add-on expenses (childcare, health insurance), and any applicable deductions. Melson-variant worksheet (with Delaware and Hawaii).
Can Montana child support be modified after the divorce?
Yes. Either parent can request a modification if there has been a material change in circumstances, such as a significant change in income, custody arrangements, or the needs of the child. The court will recalculate support using the same statutory formula.
What is the Montana child support formula?
Per-parent income after taxes − personal allowance → primary allowance by income share + SOLA → parenting-day offset.
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Start My Free MontanaEstimate →This tool provides educational estimates based on Montana family law and does not constitute legal advice. Child support calculations are approximations of the statutory formula and may differ from court-ordered amounts. Consult a licensed Montana family law attorney before making decisions. Primary statute: MCA §40-4-204; ARM Title 37, ch. 62.