The property tax history on a Big Sky listing describes how the seller used the home. Under the residential tax structure Montana put in place for 2026, the rate follows the owner's use. When a home sells, it resets to the buyer's use, but only after a delay that is set by the calendar. A full-time resident who buys a former vacation rental can pay the higher rate for months before getting any relief. A second-home buyer who purchases a longtime primary residence keeps the seller's lower rate until the year ends, and then it goes away.
Big Sky has more second homes than anywhere else in the Gallatin Valley, and it sits across two counties. That makes this delay more costly here than in most places.
The rate attaches to how the home is used
The Montana Department of Revenue's 2026 tax information page lays out two tracks for residential property. Qualifying primary residences and long-term rentals get a tiered rate that applies to market value in slices:
| Portion of market value | 2026 rate for primary residences and long-term rentals |
|---|---|
| First $378,000 | 0.76% |
| $378,001 to $756,000 | 0.90% |
| $756,001 to $1,511,999 | 1.10% |
| Over $1,512,000 | 1.90% |
Second homes, short-term rentals and vacant residential lots pay a flat 1.90% on their full value. To count as a primary residence, the owner generally has to live in the home at least seven months of the year. Long-term rentals qualify when they're rented in stays of 28 days or more for at least seven months of the year.
These rates aren't the bill. They turn market value into taxable value. The bill comes from applying the combined mills of every taxing jurisdiction that covers the parcel.
None of this is tied to the house itself. The classification records who owns the home and how they use it, so a sale reopens the question.
What happens to the rate after you close
The Department of Revenue's homestead FAQ walks through the sale scenarios. Put in order, they look like this:
- If the home already had a reduced rate, whether as a homestead or a long-term rental, that rate stays on the property for the rest of the calendar year after the sale.
- The new owner has to enroll for the reduced rate to continue past December 31. Enrollment for 2027 is open now and closes March 1, 2027.
- If the home was never enrolled and you bought it after the 2026 deadline, which was March 20, 2026, it's taxed at the flat 1.90% for 2026. A buyer who meets the requirements can claim a refund equal to the difference between the flat-rate tax and the homestead-rate tax. The window to file that claim runs from January 1 to May 31, 2027. That buyer still has to enroll for the reduced rate to apply in 2027.
- Enrollment isn't automatic after a sale. The FAQ says you must enroll if the property was sold or transferred, if ownership changed, or if you bought or built a new home.
Play that out with two Big Sky purchases closing this fall.
A family moving full time into a condo that used to be a short-term rental gets a 2026 bill figured at 1.90% if the seller never enrolled it. They pay that bill and can't file for the refund until January. Even then, the refund depends on actually meeting the seven-month residency test.
A buyer purchasing a mountain home as a second residence from a seller who lived there year-round gets the seller's reduced rate through December. Starting in 2027, the home is taxed at 1.90% under the new owner's use. A carrying-cost estimate built from the seller's bills would underestimate the second year.
What the gap looks like at Big Sky prices
The math below applies the 2026 rates to three market values. It shows taxable value only, because the final tax depends on the mills for each parcel.
| Market value | Taxable value at tiered rate | Taxable value at flat 1.90% | Difference |
|---|---|---|---|
| $750,000 | $6,220.80 | $14,250 | $8,029.20 |
| $1,500,000 | $14,458.80 | $28,500 | $14,041.20 |
| $4,000,000 | $61,862.80 | $76,000 | $14,137.20 |
The difference stops growing once a home passes about $1.512 million. Above that point, even a qualifying primary residence pays 1.90% on each additional dollar, so the gap between the two classifications levels off at roughly $14,137 of taxable value. A $750,000 condo used as a second home has more than twice the taxable value of the same condo used as a primary residence. A $4 million home has about 23% more.
That changes which Big Sky buyers feel the reset most. Condos and townhomes in lower price ranges see the largest percentage swing. Luxury homes see a dollar gap that's large in absolute terms but makes up a smaller share of total carrying cost. Either way, you only get the real dollar figure by multiplying that taxable-value gap by the mills where the property sits.
Why the county line matters here
Big Sky sits partly in Gallatin County and partly in Madison County, and the 2026 change looks different on each side. Montana Free Press published preliminary county projections in May 2025. For 2024 to 2026, they estimated non-homestead residential bills up 71% in Gallatin, owner-occupied bills down 12%, and long-term rental bills down 26%. Madison's estimates were up 44%, down 17%, and down 29%. These are projections, not measured bills.
The same analysis found that non-homestead residences made up 72.2% of Madison County's tax base, compared with 15.4% in Gallatin. On the Madison side of Big Sky, second homes are the main part of the tax base.
The mills differ too. County mills are the same across a county, but school district and other jurisdiction levies can vary from one parcel to the next, according to the Department of Revenue. We haven't found a published side-by-side of total levies for comparable Big Sky parcels in the two counties. Treat each address as its own calculation.
The change has drawn a lot of attention in Big Sky. In August 2025, the Big Sky Chamber of Commerce hosted Department of Revenue Director Brendan Beatty at a forum moderated by Big Sky Resort Area District board member John Zirkle, as Explore Big Sky reported. Zirkle said primary-residence owners eligible for the homestead rate could see decreases, while many non-primary owners and short-term rental operators would likely see significant increases. Beatty told attendees, "With the tax shift in the new legislation, I'm gonna pay more taxes."
The first bills under the new rates are due soon
According to the Department of Revenue, county treasurers usually mail real property tax bills in late October. The first half is due November 30 or within 30 days of the notice's postmark, whichever is later. The second half is due May 31. For Big Sky owners, the bills arriving over the next few weeks are the first ones calculated under the 2026 structure. For anyone under contract, they're the first real evidence of how a property is classified.
The structure is also being challenged in court. Sen. Greg Hertz, Sen. Tom McGillvray and former legislator Keith Regier sued in Gallatin County District Court in January 2026 to invalidate SB 542, the law behind the change, the Daily Montanan reported. Montana Free Press reported that a successful challenge could return the state to its 2024 tax system. In the most recent coverage we found, from June 11, 2026, the Daily Montanan reported the case was still pending, and the plaintiffs' lawyer said they were not seeking to claw back benefits already received. We haven't seen a ruling reported since then. Plan around the structure as it stands now, and know that it could change.
FAQ
How can I see whether a Big Sky property is enrolled for the reduced rate? The Department of Revenue runs a Homestead Enrollment Verification Tool. You search it by the property's geocode. The same portal handles enrollment and ownership updates.
Does a homeowner have to re-enroll every year? No, as long as nothing has changed. An owner who received the 2025 property tax rebate and still owns and lives in the same home for at least seven months of 2026 is already enrolled. A sale, transfer or move requires a new enrollment.
What if I move mid-year from one primary home to another? The department allows time in a prior home and a replacement home to count together toward the seven-month test in some 2026 move situations. Its examples treat a July-to-August move differently from a July-to-September move, so check the exact dates against the FAQ or call the department at 406-444-6900.
Is the rate on a long-term rental different from a homestead? Single-family homes, townhomes and condos used as qualifying long-term rentals get the same tiered rate as a primary residence. Multifamily long-term rentals pay a flat 1.10%.
If you're pricing a Big Sky purchase or getting ready to sell, Chelsea Stewart Real Estate can help you separate the seller's tax history from the carrying cost you'll actually pay, and confirm with the county treasurer and the Department of Revenue which side of the county line and which classification apply to that address. Request a free home valuation and we'll go through the numbers for your property.
This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.
