The statutory ceiling
This rate is fixed by statute and no bidding can reduce it, so every certificate sold carries it in full. It is a ceiling only in the sense that nothing pays more. There is no statutory minimum return.
No minimum, because there is nothing to compete away
Montana sets no statutory minimum return because it sets no variable one either. The rate is fixed and nothing is bid at the sale, so what you earn depends on how long the certificate stays unpaid, not on what you gave up to win it.
How interest accrues
Interest runs at 5/6 of 1 percent a month, which is 10 percent a year, on the whole amount the assignee paid. Mont. Code Ann. 15-18-114(2)(a) is explicit: on redemption the treasurer pays the assignee the amount the assignee paid the county for the property tax lien, plus any subsequent taxes the assignee paid under 15-18-112, plus interest at the 15-16-102 rate from the date of each payment to the date of redemption. Because 15-17-323(1)(a) fixes the assignment price at the payoff, there is no premium to dilute the base. The 2 percent delinquency penalty is a one time charge already built into the payoff the assignee buys, not an extra return on top. The county's assignment fee is a cost under 15-17-121(3)(a)(iii) and rides on the lien. Montana sets no minimum return, so a lien redeemed a month after assignment earns about a month of interest and nothing more. Subsequent-year taxes may be added to an existing assignment only between June 1 and July 31, or after the date in 15-16-102(4)(b) and before July 31 for a parcel in the property tax assistance program, and they earn the same rate from the date paid.
Why nothing is bid at this sale
Nothing is bid in Montana because nothing is auctioned. Montana repealed its tax lien sale. Title 15, chapter 17, part 2 is captioned "Tax Lien Sale (Renumbered and Repealed)" in the official code, 15-17-201 through 15-17-214 are shown as repealed, and the one surviving section, old 15-17-212, was renumbered 15-17-125 and now describes an ATTACHMENT rather than a sale. Under 15-17-125(1)(a) the treasurer attaches the lien and the county is the possessor of it unless it is assigned under 15-17-323. Under 15-17-323(1)(a) the treasurer must assign that lien to any person who first mails the assessed owner a notice of pending assignment and then pays the delinquent taxes, penalties, interest and costs. The amount is fixed by the payoff and the rate is fixed by 15-16-102, so neither price nor yield is competed. What a county allocates is access: 15-17-323(1)(b) directs each treasurer to write a policy for the case where more than one person seeks the same assignment, developed with the county clerk and recorder and the county attorney, and those policies differ. Madison County serves the counter first come, first served and breaks a tie by drawing numbers from a cup. Yellowstone County takes one ranked parcel list per investor by noon on the day before assignment day and runs a randomized snake draft at 10:00 a.m., then sells whatever is left first come, first served. Gallatin County takes ranked lists by noon on August 30 and runs a lottery on September 1. Those dates and fees come from each county's own published timeline and move with the year, so read them as the three shapes a policy takes rather than as fixed dates. TWO STATUTORY STEPS LOOK LIKE A SALE HERE AND ARE NOT AN INVESTOR AUCTION. The first is the attachment itself on the first working day in August, which several county offices still call the tax lien sale and advertise in the newspaper each summer; it transfers nothing to an investor, it moves the lien to the COUNTY, and the published notice under 15-17-122 is a warning to delinquent owners rather than a bidder notice. The second is the county tax-deed land auction under 7-8-2301, a genuine public auction but of land the county already owns after taking its own tax deed, ordered by the county commissioners within 6 months of acquiring title at a price the board fixes in advance. Neither one is a tax lien auction, and Montana holds no tax lien auction of any kind. A Montana sheriff's sale or foreclosure sale notice is a mortgage foreclosure and has nothing to do with the tax lien process.
When the certificates sell
There is no sale date to attend. The statewide calendar is fixed by statute rather than published per county. The treasurer publishes or posts the notice of pending attachment on or before the last Monday in June, mails the assessed owner a notice at least 2 weeks before attaching, and attaches the tax lien no later than the first working day in August. An investor who wants an assignment must mail the assessed owner the statutory notice of pending assignment by certified mail at least 2 weeks before paying, and that notice may not be sent earlier than August 15 or more than 60 days before the purchase, so the earliest practical assignment date in any county is about August 29. Assignments of unclaimed liens remain available from the treasurer year round after that.
The headline figure is a ceiling, not a forecast. To see what a certificate actually pays over a real holding period, run the numbers in the yield calculator, and compare Montana against other states on interest rates by state.
Verified Sep 10, 2026 against Montana statutes.
Tax Sale Atlas publishes educational information about public tax sale processes. This is not legal, financial, or investment advice. Rules, dates, and fees change; confirm with the county office before you bid.