Child Support in Montana

The Child’s Needs Take Priority

In Montana, child support is based on the principal that the child’s needs are the parents’ first priority. Child support payments are designed to meet those needs, according to both parents’ financial ability. A court could order either parent or both of them to make payments, but generally the non-custodial parent – the parent who spends less than half time with the child (or children) – actually pays support.

The custodial parent – the parent who has the most time with the child – remains responsible for child support too, but the law assumes that this parent spends the required amount directly on the child.

The state sets a base support amount according to the child support guidelines. The guidelines are simply a fee schedule based on factors like the parents’ financial abilities, custody arrangement (often called a parenting plan) and the number of children to be supported. The final amount of support that a court will order, however, could be quite different. Other costs including the child’s medical care and day care must be included. Likewise, a court can adjust the amount of support either up or down to better meet the child’s needs.

How to Calculate Child Support Payments

The Montana Department of Public Health and Human Services provides worksheets and instructions to walk you through the child support process. While you will need to collect a stack of financial information to complete a request (or respond to one) for child support, a good place to start is the financial affidavit – it’s a form you use to explain your income and other assets, as well as your debts or obligations. The financial affidavit includes tax and insurance information, expenses involved in caring for all of your children, and your income, among other things.

For income, you must include your earnings and other benefits from nearly every source. It is your salary, wages, bonuses and commissions from your job, but also any pension or severance pay. Income is also money that comes from any royalties, dividends, a trust, or rents. If you are unemployed, chances are you still have income for child support purposes in the form of social security, workers’ compensation, unemployment or disability benefits. Spousal support received counts too, and in some cases, a court could even impute income based on the value of assets like a vacation home or a car.

You can exclude some items like the money a new spouse brings in, SSI, food stamps (SNAP), adoption subsidies, and any means-tested veteran’s benefits or public assistance benefits.

If you think you can reduce your child support payments by working less or not at all, think again. A court can impute income – meaning, assign an amount you should be making – based on recent work history, qualifications, and opportunities.

Completing your financial affidavit gives you good headway toward what your child support responsibility will be, but to make the calculation you'll need some other proof of assets and costs, as well as all of the other parent’s financial information.

For a list of documents you will need, see the Worksheet instructions. For more information on what to include as income, what you can leave out, and what you can later deduct, see the Administrative Rules of Montana on Guidelines.

Challenging the Amount of Support

Once you have worked through the worksheets, the outcome will be an amount of support that the state presumes to be adequate and reasonable for your child. Sometimes, however, the total amount or the way it is divided is unfair to a parent or the child. Before a child support order is in place, either parent can ask to adjust the amount of support. Where a parent provides clear and convincing evidence that the amount would be unjust (this is called rebutting the presumption), the court will either increase or decrease the amount of support based on the following factors:

  • the child’s financial resources
  • the parents’ financial resources
  • the standard of living the child would have enjoyed had the marriage lasted
  • the child’s physical, emotional, educational, and medical needs
  • the child’s age
  • the child’s day care costs
  • the parenting plan, and
  • the needs of any person, other than the child, whom either parent is legally obligated to support.

Modifying the Amount

Once a child support order is in place, in most circumstances you must wait 12 months before you can ask the court to change (modify) it. An exception to this is if the order did not include the child’s medical care; that can be added at any time.

To justify a modification, you will need written consent by both parents or will have to show a substantial and continuing change in circumstances that makes it too difficult for you to make payments at the current rate. A common change in circumstance is the loss of a job. A court can’t retroactively apply a modification, however. So even if a parent loses a job, for example, payments continue at the current (ordered) rate until a court changes it, and then the change applies only to payments going forward.

Ending Child Support

Child support payments terminate when the child becomes emancipated or by the child’s graduation from high school or 19th birthday, whichever of the two occurs later. Parents may extend child support for a longer period by written agreement. A court, too, could order payments for a longer period based on the child’s needs.


In addition to the links above, see the Montana Child Support Guidelines Packet and other resources provided by Montana’s Child Support Enforcement Division, including how to establish paternity or enforce a child support order.

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