Yellowstone County, MT follows the Montana statutory schedule. This page shows that schedule, the county's own website, and the late penalty — the county can still set its own dates, so confirm before you pay.
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…until first half — December 1, 2026
Instalment
Due date
Notes
First half
December 1, 2026
One-half is payable by 5 p.m. November 30, or 30 days after the notice is postmarked if later.
Second half
June 1, 2027
The remaining one-half is payable by 5 p.m. May 31.
Schedule: mca.legmt.gov · Montana statute · not yet county-verified
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Statewide schedule — read this before you rely on it
County treasurers use the statutory November 30 and May 31 dates, with the same 30-day postmark extension applied statewide. Most counties in this state follow these dates.
Delinquent tax draws interest at 5/6 of 1% per month plus a 2% penalty.
The Department of Revenue mails the annual tax notice in the fall, timed to the November 30 first-half date.
Yellowstone County at a glance
Population: 170,843 (Census estimate, 2023) — the 1st largest of 56 Montana counties and county equivalents.
Typical tax bill: $2,556 a year (median for owner-occupied homes, ACS 2022 5-year estimate) — the Montana median is $2,419.
Land area: 2,633.3 sq mi, about 64.9 people per sq mi.
By post: mail to the county treasurer; the postmark usually counts, not the arrival date.
In person: the treasurer's office, with your bill or parcel number.
Escrow: if your mortgage escrows taxes, the servicer pays — you still owe any shortfall.
Is this county verified?
Not yet. Yellowstone County is on the queue: we publish a county's own published dates once they have been checked against the county website. Ask for it and it moves up. Until then, the Montana statutory schedule above is the reliable starting point.
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StacyApproved is an independent reference and is not a government agency. Deadlines change and exceptions apply — always confirm with your county treasurer using the official link on this page. Nothing here is tax, legal or financial advice.