Big Sky Second Home Property Tax Explained for Buyers

A buyer looking at two Montana listings this summer might see nearly identical price tags. One sits on a quiet street in Bozeman, the kind of house someone moves into full time. The other sits in Big Sky, a few minutes from a chairlift, the kind of place a family visits eight or ten weeks a year. Same square footage. Same rough valuation. Very different tax bills, and the gap has nothing to do with the county assessor's opinion of the house. It comes down to a single classification question buried in state law: does anyone live here seven months out of twelve.

That question now decides which property tax rate applies to a Montana home, and Big Sky's entire housing stock was built around the wrong answer.

Two Rate Structures, One Assessor

Montana rewrote its property tax rules with two bills passed in the 2025 legislative session, Senate Bill 542 and House Bill 231. Together they created what the state now calls a homestead system, and it fully takes effect for the 2026 tax year, with bills going out in November. A primary residence, meaning a home owned by an individual or a couple and lived in for at least seven months of the year, qualifies for a graduated rate that starts low and climbs only for the most expensive properties in the state, reaching the top rate of 1.90 percent once a home's value passes roughly $1.58 million. A long-term rental with the same tenant for at least seven months qualifies too.

A second home, a ski condo used a handful of weeks a year, or a short-term rental gets none of that grading. It pays a flat 1.90 percent on the full assessed value, from the first dollar. There is no middle tier. The Montana Department of Revenue runs enrollment for the homestead exemption through its own portal, and the first application window closed on March 1, 2026. Owners who received the 2025 rebate were automatically enrolled going forward. Everyone else has to apply and prove primary-residence status.

For most of Montana, this restructuring was a relief bill. State figures show roughly eight in ten homeowners saw their 2025 tax bill drop by more than 5 percent compared to 2024, a level of relief the old system would have delivered to only about one in ten owners. That is the story most of the state is living.

Why Big Sky Doesn't Get to Live That Story

Big Sky isn't most of the state. Census estimates covering 2019 through 2023 put the town's vacancy rate at 64.9 percent, the highest of any community in Montana, meaning close to two out of every three housing units sit empty most of the year as seasonal or recreational property. The same data puts Big Sky's median home value at roughly $1.8 million, the top percentile among Montana towns, and its home-price-to-income ratio at 17.2, well above Whitefish's 11.7 and more than double Bozeman's 8.8.

Put those numbers together and the mechanism becomes obvious. A tax code built to reward primary occupancy was applied to a town where primary occupancy is the exception. Homes in Yellowstone Club, Spanish Peaks Mountain Club, and Moonlight Basin were never marketed as year-round residences for buyers of ordinary means. They were built and sold as second homes for people whose primary address is somewhere else, which means the flat 1.90 percent rate isn't a penalty a Big Sky buyer can plan around with better paperwork. It's the rate the market was designed to land in.

This is the part that a headline about a "new second-home tax" tends to miss. The tax didn't reach into Big Sky and single it out. It applied one rule evenly across the state and Big Sky's own housing economics did the rest.

The Lawsuit Sitting Two Counties Away From the Story People Think It's Telling

None of this is fully settled. On January 21, 2026, Republican state senators Greg Hertz of Polson and Tom McGillvray of Billings, along with former senator Keith Regier of Kalispell, sued the state of Montana and the Department of Revenue in Gallatin County District Court, the same courthouse that handles closings and probate for Big Sky and Bozeman properties. Their argument isn't about second homes at all. It's about process. SB 542 started the session as a three-page bill freezing property valuations for two years. By the time it passed, it had grown into a forty-page rewrite that critics nicknamed the "Frankenstein bill," folding in the entire homestead rate structure and $90 million in one-time $400 rebates. The plaintiffs argue that combination violates the Montana Constitution's single-subject rule and its restriction on amending a bill beyond its original purpose.

"If constitutional procedures can be ignored for one bill, they can be ignored for any bill."

That's Hertz's framing, and it matters because of what the lawsuit does and doesn't ask for. Governor Greg Gianforte petitioned the Montana Supreme Court in March to take over the case and expedite a ruling, warning that a win for the plaintiffs could unwind the tax rates and claw back the rebates already paid out. The Supreme Court declined the request on March 31, sending the case back to the district court to proceed on its own timeline. Weeks later, the Montana Republican Party itself filed a brief siding with the plaintiffs against its own governor's flagship law. As of a June update, the case was still working its way through the district court with no ruling yet, and it will still be sitting there when the Legislature reconvenes in January 2027.

Here's the piece worth sitting with. The plaintiffs aren't asking the court to lower the rate on second homes. Hertz has said the suit doesn't even seek to claw back the rebates. If the plaintiffs win on the narrow procedural question they're actually arguing, a judge could strike the whole law down and revert Montana to its prior tax structure, the one without a homestead discount for anyone, primary resident or not. A win framed publicly as a fight over an unfair second-home tax could just as easily erase the discount Bozeman homeowners are currently enjoying, without touching the underlying instinct to tax non-primary property at a higher rate. A Big Sky buyer waiting for this lawsuit to solve their tax bill is waiting for the wrong outcome.

What This Actually Changes for a Purchase This Year

None of this changes whether a Big Sky property is worth buying. It changes what belongs in the carrying-cost conversation before an offer goes in.

• Ask what tax class the current owner has been filed under, and don't assume a prior owner's homestead status transfers with the sale. It doesn't.
• Model the flat 1.90 percent rate as the baseline for any property that will function as a second home, not the graduated rate advertised in generic Montana tax guides.
• If a property sits inside Big Sky Owners Association jurisdiction, which covers more than 2,400 properties across over 8,000 acres in Gallatin and Madison counties, factor in that assessment separately from the county tax bill. BSOA raised its annual dues 4.3 percent to $545 in 2025, citing a jump in liability and homeowners insurance costs from $36,000 to $82,000 in a single year. That's a separate line item from state property tax, and it moves independently of anything happening in the Gallatin County lawsuit.
• Treat the district court case as a live variable, not background noise. Ask a Montana-licensed tax professional or real estate attorney where the case stands before closing, since a ruling could shift the ground the deal is standing on.

FAQ

Does a Big Sky condo automatically get taxed as a second home? Not automatically by location alone. The classification depends on occupancy, specifically whether the same individual or couple lives there at least seven months a year and has enrolled through the state's homestead process. Most Big Sky units simply don't meet that bar because of how the market was built, but the classification itself is based on use, not geography.

If the lawsuit succeeds, will second-home rates go down? Not necessarily. The plaintiffs are challenging how the law was passed, not the substance of taxing second homes at a higher rate. A full win could strike the entire law, including the homestead discount other Montanans are currently receiving, without guaranteeing any relief for non-primary property.

Is this the same thing as Big Sky's resort tax? No. The homestead property tax classification is a state-level system tied to how a county assessor values and bills the property annually. Big Sky's separate 4 percent resort tax applies to short-term lodging and luxury goods purchased within the district, a different tax entirely with its own registration and remittance rules.

Every one of these numbers is a starting point for a conversation, not a final answer, and the district court case means today's rate could look different by the time the Legislature meets again. Charlotte Durham & Co. tracks these shifts as part of how we price and position property across Big Sky, Moonlight Basin, and the surrounding valley. If you're weighing a purchase against this backdrop, Start Your Montana Luxury Journey with a conversation grounded in what the numbers actually mean for your specific property, not the generic version.