When taking into account Montana has a third of the population of Idaho, extrapolation would show Idaho facing hundreds of millions of dollars in revenue losses from personal income tax changes alone, Gannon said. Gannon was the the lone committee member opposed to introducing the bill with differences still outstanding on the fiscal cost. Further debate on the cost of conforming to federal tax changes is expected when the bill returns to committee for a public hearing. A report from the Idaho State Tax Commission indicates some of the personal income tax provisions for tax years 2025 through 2028 carry greater uncertainty in cost than others. What further holdbacks would mean for each agency in the state remains to be seen, but there have been some early indicators.