Idaho and Montana at a glance
Moving between Idaho and Montana changes more than the scenery. On a $60,000 salary, Idaho leaves $28,084 a year after taxes, rent, food, energy and gasoline; Montana leaves $26,630.
Idaho comes out ahead by $1,453 a year ($121 a month). The calculation starts from the same gross pay in both states, subtracts federal tax, Social Security and Medicare, then each state's own income tax, and then the population-weighted cost of a one-bedroom rental, groceries, home energy and gasoline across 1,934,262 people in 44 counties in Idaho and 1,116,875 people in 56 counties in Montana.
Taxes: what each paycheck loses
Federal income tax ($5,072) and FICA ($4,590) on $60,000 are the same on both sides of the border. State income tax takes $2,137 in Idaho and $2,402 in Montana, which leaves take-home pay of $48,201 and $47,937.
At $100,000
At $100,000 take-home pay is $74,644 in Idaho and $74,139 in Montana, a difference of $504. The gap widens with income because graduated state brackets take a growing share.
Living costs
One-bedroom rent averages $1,132 a month in Idaho and $1,223 in Montana, so Idaho is $91 a month cheaper for housing. Food costs $3,436 a year in both, because the USDA Thrifty Food Plan is a national figure; home energy $1,553 and $1,655, and gasoline $1,549 and $1,542. Together the basics cost $20,118 a year in Idaho and $21,306 in Montana.
What the Census adds
Median household income is $77,800 in Idaho and $72,509 in Montana. Homeowners pay a median of $2,038 a year in property tax in Idaho and $2,693 in Montana. Commuters travel 21.6 minutes each way on average in Idaho and 19.1 in Montana.
Method
Taxes use the 2025 rules for a single filer with wage income only and the standard deduction. Housing and living costs are county figures from HUD (one-bedroom Fair Market Rent), the USDA Thrifty Food Plan and state energy prices from the Energy Information Administration, averaged across each state's counties and weighted by population, so large counties count more. Local income taxes are not included. Counties differ widely inside every state, so use the county pages for a specific place.