How to Use the Montana Child Support Calculator
Enter what you know and press Calculate Estimate. The calculator follows the Montana Child Support Guidelines (ARM 37.62.101-148) and the CSSD 404.2 tables effective February 1, 2026, using the steps of Worksheet A.
- Enter each parent's gross monthly income. The calculator annualizes it and estimates federal and Montana income tax and Social Security.
- Choose the number of children and the parent the children live with most of the time.
- Enter the days a year the children spend with the other parent. More than 110 days with each parent changes the result.
- Add child care (after the dependent care tax credit) and the children's health insurance as monthly amounts, and say who pays them.
Your numbers are sent with the form, not placed in the page address, and this site does not store them. This is a planning estimate. A Montana court or CSSD sets the actual amount.
Montana Child Support in 2026
Looking for Montana child support guidelines for 2026? The rules (ARM 37.62.101-148) have not changed, but CSSD updates its tables every year with the federal poverty guidelines and the IRS mileage rate. The tables in policy 404.2, effective February 1, 2026, set:
- Personal allowance for each parent: $20,748 a year.
- Primary child support allowance: $6,224 a year for one child.
- Long-distance parenting: IRS mileage rate $0.725 a mile, standard expense $1,450.
Montana Allowances and SOLA Factors (2026)
| Children | Primary child support allowance (per year) | SOLA factor |
|---|
| 1 | $6,224 | 14% |
| 2 | $10,374 | 21% |
| 3 | $14,523 | 27% |
| 4 | $16,598 | 31% |
| 5 | $18,673 | 35% |
| 6 | $20,748 | 39% |
| 7 | $22,822 | 43% |
| 8 or more | $24,897 (8 children) | 47% |
The primary allowance is 30% of the personal allowance for the first child, 20% for each of the second and third, and 10% for each additional child.
Parenting Days
If the children live primarily with one parent and spend 110 days or fewer a year with the other parent, there is no adjustment. If a child spends more than 110 days with each parent, each parent's obligation for that child is reduced by 0.69% (.0069) for every day over 110 the child spends with that parent, and the amounts are offset. A day is the majority of a 24-hour period, midnight to midnight unless agreed otherwise.
Montana Child Support Examples
In each example the children live with Parent B. Amounts are monthly and come from this calculator, so taxes are estimates.
Example 1: One child
A earns $5,000 and B earns $3,000 a month. A's share of the $6,224 primary allowance plus SOLA gives $7,851 a year: $654 a month.
Example 2: Two children with child care and insurance
A earns $6,000 and B earns $4,000. B pays $500 a month child care and $200 insurance. A owes $17,365 a year: $1,448 a month.
Example 3: 150 days with the other parent
A earns $7,000 and B earns $3,000, one child, 150 days with A. After the parenting days adjustment A pays $553 a month.
Example 4: Low income
A earns $1,500 a month. Income after deductions is below the personal allowance, so A pays the minimum: $109 a month.
These are illustrations produced from the guidelines, not court rulings.
Frequently Asked Questions About Montana Child Support
Is this the official Montana child support calculator?
No. ChildSupportCalculator.xyz is an independent tool and is not affiliated with the State of Montana, its courts or CSSD. It applies ARM 37.62.101-148 and the 2026 CSSD tables. A court or CSSD sets the actual amount.
What formula does Montana use for child support?
A version of the Melson formula: each parent keeps a personal allowance, the children get a primary support allowance plus supplements shared by income, and a standard of living adjustment (SOLA) is added.
What is the Montana personal allowance in 2026?
$20,748 a year for each parent, from the CSSD 404.2 tables effective February 1, 2026.
What is the minimum child support in Montana?
Generally 12% of income after deductions. If income after deductions is at or below the personal allowance, a lower minimum from the income ratio table applies.
How many days change child support in Montana?
If a child spends more than 110 days a year with each parent, each parent's obligation is reduced by .0069 for each day over 110 with that parent and the amounts are offset.
Is child care included in Montana child support?
Yes. Child care needed for work, reduced by the dependent care tax credit, is added to the primary allowance and shared by income, and the parent who pays gets credit.
Does Montana use gross or net income?
Montana starts with gross income and subtracts taxes, Social Security and other allowed deductions, then the personal allowance.
Does the Montana calculator need my personal details or a login?
No. This site needs no login and does not store your numbers.
Official Montana Child Support Resources
Published: October 19, 2026
Last reviewed: October 19, 2026
Researched and reviewed by Eric John, founder and editor, using official state statutes and guidance. How we build and check our calculators · Corrections
