IFTA Tax Rates in Montana (2026)

Key numbers at a glance

IFTA tax rates in Montana

The rates below are what your base state applies to Montana miles when processing your quarterly IFTA return. Figures are as of Q4 2026 — confirm the current official IFTA matrix before filing, especially with suspension proposals in the air (more on that below).

Two Montana quirks matter to IFTA filers. First, the gasoline-diesel split: unlike states that tax both fuels identically, Montana's 33.0/29.75 structure means your fueling math differs by fuel type. Second, reporting: the IFTA Clearinghouse tax matrix notes that Montana no longer requires gasoline, gasohol and ethanol to be reported on the IFTA return — diesel (special fuel) is the line that matters — but verify your base state's current instructions each quarter, since reporting notes change with the matrix. One caution on all-in comparisons: the Tax Foundation's July 2026 table shows Montana at 33.75 cents gasoline and 30.5 cents diesel because it adds about 0.75 cents of per-gallon fees on top of the state rates; the MDT table figures above are the statutory rates your receipts and matrix lines are built on. And watch 2027: Montana legislators publicly debated suspending the state fuel tax during the October 2026 price spike — nothing was enacted, but a suspension would change these numbers mid-year, which is exactly why the matrix check exists.

How Montana IFTA affects your filings

Montana is a mileage state: I-90 and I-15 alone can put 500–700 Montana miles on a single run, so the diesel line on your return grows fast even at a moderate rate. The math: Montana miles ÷ fleet MPG × 29.75 cents. At 6.5 MPG, Montana costs 4.58 cents per mile in fuel tax — 600 miles means 92.3 taxable gallons and $27.46 owed. A regional carrier running 12,000 Montana miles a quarter at 6.5 MPG owes roughly $549 before pump credits.

Credits follow the pump. Montana diesel receipts carry the 29.75-cent tax embedded in the price, so fueling at Billings or Bozeman before a Wyoming or Idaho leg pre-pays tax on gallons you were going to burn anyway — the neutral strategy when rates are close. The exposure runs the other direction: cheap Wyoming or North Dakota fuel credits those states, not Montana, and the 5.75–6.75 cent gaps show up as a due balance four times a year. Keep receipts matched to ELD or GPS distance records, recompute MPG every quarter (mountain grades and winter blends move it more than flatland carriers expect), and file on time even at zero net — late filings typically draw $50–$100 penalties plus interest. The IFTA calculator runs the per-state math; the fuel surcharge guide handles the rest of the pump price.

Fueling strategy: Montana versus its neighbors

Montana sits in the middle of a cheap-neighbor region — only Idaho is higher on diesel among its neighbors. Rates below are per gallon, per the Tax Foundation's July 2026 state table (Montana shown from the MDT rate table above).

The play: westbound on I-90 toward Spokane, fuel in Montana before the Idaho line — Idaho's 33.0 cents is the region's high, and prepaying Montana's 29.75 beats owing 3.25 cents more later. Eastbound toward the Dakotas, the calculus flips: Wyoming (24.0) and North Dakota (23.0) are the cheap fuel, so fill there before re-entering Montana miles; running Montana on Wyoming diesel leaves 5.75 cents per gallon due, roughly $8.90 per 1,000 Montana miles at 6.5 MPG. Distances between fuel stops are long here — plan tanks against the rate map, not the next exit. Track every state on the IFTA rates by state hub, confirm quarterly figures in the IFTA Clearinghouse rate matrix, and pull Montana's official table from the Montana Department of Transportation fuel tax rates page.