How child support is calculated in Montana

How the guideline works, what the official calculator needs, and the low-income and health insurance rules.

Checked against official sources: Oct 25, 2026.

Short answer

Montana uses a version of the Melson formula, which looks at both parents' incomes and the children's basic needs. Montana uses its own version of the Melson formula. Each parent first keeps a personal allowance for basic needs (130% of the federal poverty level, $20,748 a year in the tables effective February 1, 2026).

Model
Melson formula
Official calculator
Official Montana child support calculator

Where the real number comes from in Montana

Montana uses its own version of the Melson formula. Each parent first keeps a personal allowance for basic needs (130% of the federal poverty level, $20,748 a year in the tables effective February 1, 2026). Then a basic amount for the children is shared by the parents in proportion to their income, and if a parent has income left over, a further share (standard of living adjustment) is added. Parenting days, child care and health costs also count.

Law: Mont. Code Ann. 40-4-204, 40-5-209; Admin. R. Mont. 37.62.101-148

We don't estimate Montana's amount here: its formula uses both parents' incomes and other facts, and a home-made number could mislead you. The official tool gives the real starting number:

Official Montana child support calculator

The Montana guideline, step by step

Montana uses its own version of the Melson formula. Each parent first keeps a personal allowance for basic needs (130% of the federal poverty level, $20,748 a year in the tables effective February 1, 2026). Then a basic amount for the children is shared by the parents in proportion to their income, and if a parent has income left over, a further share (standard of living adjustment) is added. Parenting days, child care and health costs also count.

Law: Mont. Code Ann. 40-4-204, 40-5-209; Admin. R. Mont. 37.62.101-148

If the paying parent earns little in Montana

A minimum contribution is set in every case. If your income after deductions is at or below the personal allowance, the minimum is a small share of your income from a table (0% to 11%). If your income is above the personal allowance but the calculated support is under 12% of your income after deductions, the minimum is 12%.

Law: Admin. R. Mont. 37.62.126

State guidelines may not treat time in jail or prison as choosing not to work, when support is set or changed.

Law: 45 CFR 302.56(c)(3)

Health insurance in Montana

Every Montana support order must include medical support, usually health insurance. A parent who can get reasonable-cost employer health coverage may be required to provide it. If an order has no medical support, or medical support is violated, support can be modified right away.

Law: Mont. Code Ann. 40-4-208(2)(c), 40-5-804

The model in plain words

In a Melson state, support is built in steps: a self-support amount for each parent, the child's primary needs, and an extra share when income allows.

Every state must have one set of child support guidelines, review them at least every 4 years, and use the guideline amount unless a written finding says it would be unjust.

Law: 45 CFR 302.56

In nearby states

Steps to a support amount in Montana

  1. Collect proof of income

    Recent pay stubs and last year's tax return are the usual starting point.

  2. Run the official numbers

    Get the guideline amount from Official Montana child support calculator.

  3. Add the extra costs

    Insurance and child care often go on top of the basic amount.

  4. Get an order

    The agency can set up an order: contact Montana DPHHS Child Support Services Division (CSSD) (1-800-346-5437) · Apply online

Where to get free help in Montana

Questions about the Montana guidelines

How is child support calculated in Montana?

Montana uses its own version of the Melson formula. Each parent first keeps a personal allowance for basic needs (130% of the federal poverty level, $20,748 a year in the tables effective February 1, 2026). Then a basic amount for the children is shared by the parents in proportion to their income, and if a parent has income left over, a further share (standard of living adjustment) is added. Parenting days, child care and health costs also count.

Is there an official child support calculator for Montana?

Yes: Official Montana child support calculator.

What if the paying parent has a low income in Montana?

A minimum contribution is set in every case. If your income after deductions is at or below the personal allowance, the minimum is a small share of your income from a table (0% to 11%). If your income is above the personal allowance but the calculated support is under 12% of your income after deductions, the minimum is 12%.

How are medical costs shared in Montana?

Every Montana support order must include medical support, usually health insurance. A parent who can get reasonable-cost employer health coverage may be required to provide it. If an order has no medical support, or medical support is violated, support can be modified right away.

Related Montana pages

Sources

Sources

Last checked: Oct 25, 2026.

Federal sources