The inflation factor for FY 2026 is 2.11%.
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 2024 (315.493) divided by the CPI for December 2021 (277.948), subtracting one, and multiplying the result by 50%.
View the Montana Department of Revenue Memo for the calculation.