Almost a year after its passage, the Montana GOP fight is intensifying over Gov. Greg Gianforte’s property tax legislation package — a signature policy effort to reduce property taxes for primary residences and long-term rentals, in part by raising rates on others.
The governor’s office on Monday petitioned the Montana Supreme Court to take up a case filed in state District Court in Bozeman in January by a group of Republican lawmakers who voted against the property tax bills during the 2025 session.
If the higher court assumes jurisdiction of the lawsuit, Gianforte said, the court could answer the legal questions about the constitutionality of Senate Bill 542, one bill central to the administration’s property tax effort. Among other questions, Gianforte’s office asked the court to affirm that SB 542 met the constitutional requirement that legislation be limited to a single subject properly aligned with a bill’s title.
In its filing with the state Supreme Court, the governor’s office argued that many aspects of SB 542 had already had a widespread impact: enabling many Montana property owners to receive rebates in 2025, providing guidance for statewide property tax assessments and influencing the local tax bills distributed by county governments.
“These cascading effects, and the time-restricted nature of tax refunds and assessments, create urgency and emergency factors making the normal litigation and appeal process inadequate,” read the governor’s petition to the court.
SB 542, sponsored by Sen. Wylie Galt, R-Martinsdale, was one major part of the Gianforte administration’s property tax relief effort, a package of bills that garnered bipartisan support. The legislation allowed for the state to issue $400 property tax rebates to many homeowners and effectively reduce residential property taxes for lower-value homes by increasing rates on higher-value properties and businesses.
The bill was paired with House Bill 231 — a legislative maneuver, set to take effect this year, that increases rates on second homes and vacation-style short-term rentals. Properties rented to long-term tenants for at least seven months of the year are exempted, if a landlord successfully files an application with the state revenue department by March 20.
The original lawsuit filed by current and former lawmakers maintained that SB 542 was impermissibly amended during the legislative process. The additional language that allowed for property tax rebates, they said, was a late-stage tactic to “buy” the bill’s passage with support from more lawmakers. The lawsuit cast that strategy as “log-rolling,” which they say the Montana Constitution aimed to prevent through the single-subject clause.
Sen. Greg Hertz, R-Polson, one of the plaintiffs in the lawsuit over SB 542 and the 2025 Senate Taxation Committee chair, defended his original lawsuit in a Tuesday morning email to Montana Free Press.
“Montanans have long prided ourselves that our Legislature is nothing like Congress in Washington, D.C. In Montana, our constitutional mandate is to debate each policy idea on its own merits, with the public having a true ability to impact the outcome through their active participation,” Hertz wrote. “We are not supposed to be allowed to cobble together bills behind closed doors that no one understands and shove it down legislators’ throats as so-called ‘must pass’ legislation. The ends do not justify the means.”
Both Hertz and other plaintiffs, including Sen. Tom McGillvray, R-Billings, said in their lawsuit that they had been harmed by provisions in SB 542 that increase property tax rates for various properties. Hertz said his primary residence in Polson, which public records show was most recently valued at $2.9 million, had its taxes increase by $7,000 after the bill’s passage, to $21,000 annually from $14,000 annually.
The state Supreme Court may decide not to intervene in the lower court’s case. While that decision is pending, litigation is slated to continue in the District Court. In his comment to MTFP, Hertz forecasted that the original lawsuit could be completed before lawmakers return to Helena for the 2027 Legislature next January.