2026 fiscal calendar
Know the tax date before it becomes a penalty date.
Tax bills, payment rules, and valuation-review windows are controlled by the local jurisdiction and the governing state framework. The verified record below separates published figures from dates that require confirmation with Montana Department of Revenue Property Assessment Division — Butte Field Office / Anaconda-Deer Lodge County Treasurer.
Effective rate
no single countywide effective rate; Montana local mill levies and special assessments vary by taxing jurisdiction. For 2026, Montana DOR homestead/long-term-rental rates are tiered at 0.76%, 0.90%, 1.10%, and 1.90% by market-value bracket.
Statement mailing
no official 2026 county-specific tax-bill mailing date was published in the sources reviewed.
Payment deadline
For tax year 2026, Montana real-property taxes are due by 5:00 p.m. November 30, 2026 for the first payment and May 31, 2027 for the second payment; if a due date falls on a weekend or holiday, the next business day applies.
Valuation protest
For the 2025–2026 valuation cycle, file Form AB-26 or appeal to the county Tax Appeal Board within 30 days of the Department of Revenue classification/appraisal notice; late informal review was available through June 1, 2026. A written protest must also be filed with the county treasurer and disputed taxes paid under protest by the tax due date.
Critical payment warning
Do not assume a grace period.
The verified county record identifies the payment timing above but does not establish a universal penalty schedule for this page. Late charges, interest, collection costs, tax-sale procedures, and lien or foreclosure timelines can depend on state law and the local collector’s process. If the deadline is close or a balance is delinquent, contact the tax collector directly and request the current payoff amount in writing.
Treat the published payment deadline as a hard operational date and retain your receipt or confirmation number.
Read the calendar in order
From assessment to collection
1. Valuation and notice
Review the assessment notice as soon as it arrives. The protest window may run from the notice date rather than from the payment due date.
2. Statement and account review
Match the tax statement to the parcel or account number and confirm exemptions, assessed value, taxing units, credits, and balance.
3. Payment confirmation
Use the official collector channel, then save the receipt, transaction reference, and date posted. A bank submission is not always the same as a county posting date.