Montana and South Dakota at a glance
Moving between Montana and South Dakota changes more than the scenery. On a $60,000 salary, Montana leaves $26,630 a year after taxes, rent, food, energy and gasoline; South Dakota leaves $32,200.
South Dakota comes out ahead by $5,570 a year ($464 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 1,116,875 people in 56 counties in Montana and 907,428 people in 66 counties in South Dakota.
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. South Dakota does not tax wages, while Montana takes $2,402 of a $60,000 salary in state income tax, so take-home pay is $2,402 higher in South Dakota.
At $100,000
At $100,000 take-home pay is $74,139 in Montana and $78,901 in South Dakota, a difference of $4,762. The gap widens with income because graduated state brackets take a growing share.
Living costs
One-bedroom rent averages $1,223 a month in Montana and $958 in South Dakota, so South Dakota is $265 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 $1,655 and $1,708, and gasoline $1,542 and $1,496. Together the basics cost $21,306 a year in Montana and $18,138 in South Dakota.
What the Census adds
Median household income is $72,509 in Montana and $75,081 in South Dakota. Homeowners pay a median of $2,693 a year in property tax in Montana and $2,724 in South Dakota. Commuters travel 19.1 minutes each way on average in Montana and 17.8 in South Dakota.
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.