The Montana Supreme Court ruled on November 4, 2026, regarding child support calculations in the case of Kathryn Joan Christofferson and Colin Orval Christofferson. The court's decision affects how child support will be calculated in their divorce and whether retroactive support should be awarded. This ruling is significant for parents navigating similar issues in divorce proceedings.

Kathryn and Colin Christofferson married in 2010 and have two children, born in 2011 and 2014. They separated in January 2021, and Kathryn filed for divorce on June 27, 2022. The Fourth Judicial District Court in Missoula County issued a decree dissolving their marriage in April 2023. Before the divorce, they agreed on a parenting plan that included child support calculations through the Child Support Services Division (CSSD) and provisions for health insurance for their children.

After the divorce decree, the CSSD issued a temporary child support order requiring Colin to pay $193 per month for both children. Kathryn contested this amount, claiming errors in the calculation regarding parenting days and health insurance costs. She filed a motion for recalculation in January 2024, seeking back support from the date of separation. Colin opposed her motion, arguing they had agreed to use CSSD for calculations.

The District Court held a hearing in February 2025, where both parties presented evidence about their incomes and expenses. The court ordered Colin to pay $684 per month in child support but denied Kathryn's request for retroactive support. Kathryn appealed this decision, leading to the Montana Supreme Court's review.

The Montana Supreme Court, led by Justice Katherine M. Bidegaray, affirmed some parts of the District Court's ruling while reversing others. The court found that the District Court had erred in adopting a child support calculation that was inconsistent with its findings regarding health insurance. The court stated, "The calculation the District Court adopted does not implement the findings it made on remand." This inconsistency arose because the District Court had ordered the children to be enrolled in a public health insurance program, yet the adopted calculation still credited Colin for private insurance premiums that were no longer applicable.

Additionally, the court ruled that the District Court abused its discretion by not awarding retroactive child support. The Supreme Court emphasized that the District Court had the authority to award retroactive support but needed to provide a legally sufficient rationale for its decision. The court noted that Kathryn had experienced financial difficulties and that both parents had contributed to the children's needs since their separation.

The court concluded that the child support calculation needed to be corrected because it did not align with the health insurance arrangement ordered by the District Court. The ruling reversed the $770 monthly support amount and sent the case back to the District Court for further proceedings to determine the correct support amount based on the established facts.

This ruling has significant implications for Kathryn and Colin, as it adjusts their child support obligations and clarifies how future calculations should be handled. It also sets a precedent for similar cases where discrepancies in child support calculations arise due to changes in health insurance arrangements.

Moving forward, the case will return to the District Court, which will be tasked with recalculating the child support amount in accordance with the Supreme Court's findings. The court will need to consider the correct presumptive support amount under the guidelines and make any necessary adjustments based on the actual expenses incurred during the relevant period.

As for appeals, it is unclear if further appeals will be made following the District Court's recalculation. However, the ruling provides a framework for how child support should be calculated in light of changing circumstances, particularly regarding health insurance and retroactive support.