How to change child support in Montana

When a change is allowed, how to ask the agency or the court, and a free letter to ask for a review.

Checked against official sources: Oct 25, 2026.

Short answer

To modify an order means to change the amount by a new order. Through CSSD: you can ask for a review once 36 months have passed since the order was entered or last reviewed.

Agency review
Every 3 years if a parent asks (federal law)
First form
Request for Review packet (from your CSSD investigator)

The rule for changing support in Montana

Through CSSD: you can ask for a review once 36 months have passed since the order was entered or last reviewed. Sooner, you must show a significant change, such as a change in physical custody, child care or medical costs, number of children, or a parent's income changing by at least 30%. By law, a court can change support only if circumstances changed so much, and for so long, that the old terms are unconscionable, or if both parents agree in writing, or when CSSD asks in a case it handles. In general, an order cannot be changed within 12 months after it was set or last changed. If the order has no medical support, it can be changed right away. A change applies only to payments due after the other parent gets notice.

Law: Mont. Code Ann. 40-4-208(1)-(2)

Can I ask for a change? Check your situation

Montana's rule: Through CSSD: you can ask for a review once 36 months have passed since the order was entered or last reviewed. Sooner, you must show a significant change, such as a change in physical custody, child care or medical costs, number of children, or a parent's income changing by at least 30%. By law, a court can change support only if circumstances changed so much, and for so long, that the old terms are unconscionable, or if both parents agree in writing, or when CSSD asks in a case it handles. In general, an order cannot be changed within 12 months after it was set or last changed. If the order has no medical support, it can be changed right away. A change applies only to payments due after the other parent gets notice.

Law: Mont. Code Ann. 40-4-208(1)-(2)

Until a new order is made, the current amount is still owed. A change can count only from the date the other parent gets notice of your request, so ask soon.

Law: 42 U.S.C. 666(a)(9)

How to ask in Montana: Ask your CSSD case investigator for a Request for Review packet. CSSD recalculates support and sends a notice; parents can correct information, agree, or ask for an administrative hearing. The process usually takes up to 180 days. Or file a motion to modify in District Court.

How to ask for a change in Montana

Ask your CSSD case investigator for a Request for Review packet. CSSD recalculates support and sends a notice; parents can correct information, agree, or ask for an administrative hearing. The process usually takes up to 180 days. Or file a motion to modify in District Court.

Write to the child support agency to ask for a review: Ask the agency to review (change) your order

Recent changes in Montana

CSSD finished its 2024 quadrennial guidelines review (report dated December 27, 2024) and updates the guideline tables yearly; the tables now in use took effect February 1, 2026 (personal allowance $20,748; primary child support allowance $6,224 a year for one child). The next review is due December 2028.

Jail, prison and support

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)

In nearby states

What to do now in Montana

  1. Find your order

    The date of the order matters for the rule.

  2. Compare with the rule

    In Montana: Through CSSD: you can ask for a review once 36 months have passed since the order was entered or last reviewed.

  3. Gather proof

    Bring proof of the change, such as pay stubs or a layoff notice.

  4. File the request

    Contact Montana DPHHS Child Support Services Division (CSSD) (1-800-346-5437) · Apply online

Where to get free help in Montana

Questions about changing support in Montana

When can child support be changed in Montana?

Through CSSD: you can ask for a review once 36 months have passed since the order was entered or last reviewed. Sooner, you must show a significant change, such as a change in physical custody, child care or medical costs, number of children, or a parent's income changing by at least 30%. By law, a court can change support only if circumstances changed so much, and for so long, that the old terms are unconscionable, or if both parents agree in writing, or when CSSD asks in a case it handles. In general, an order cannot be changed within 12 months after it was set or last changed. If the order has no medical support, it can be changed right away. A change applies only to payments due after the other parent gets notice.

Where do I file to change support in Montana?

Ask your CSSD case investigator for a Request for Review packet. CSSD recalculates support and sends a notice; parents can correct information, agree, or ask for an administrative hearing. The process usually takes up to 180 days. Or file a motion to modify in District Court.

Related Montana pages

Sources

Sources

Last checked: Oct 25, 2026.

Federal sources