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Published February 2, 2024

FY25 Inflation Factor for Mill Levy Calculation

The inflation factor for FY 2025 appears to be 2.80%, pending official verification of the number by the Montana Department of Revenue, which will come out in early April.

Per 15-10-420, MCA, “a governmental entity that is authorized to impose mills may impose a mill levy sufficient to generate the amount of property taxes actually assessed in the prior year plus one-half of the average rate of inflation for the prior 3 years.”

Additionally, the Department of Revenue shall, “calculate one-half of the average rate of inflation for the prior 3 years by using the consumer price index (CPI), U.S. city average, all urban consumers, using the 1982-84 base of 100, as published by the bureau of labor statistics of the United States Department of Labor.”

One-half the average rate of (compounding) inflation was determined by taking the cubed root of the CPI for December 2023 (306.746) divided by the CPI for December 2020 (260.474), subtracting one, and multiplying the result by 50%.

If you have any other questions, please feel free to contact Nancy Everson, Governmental Finance Director, MACo by way of email at or by phone at 406-459-2295.

Nancy Everson  |  |  (406) 449-4360