Side-by-side tax comparison between Idaho (5.8% top rate) and Montana (5.9% top rate).
| Salary | Idaho | Montana | Difference | Winner |
|---|---|---|---|---|
| $50K | $40,123 | $40,085 | −$38 | Idaho |
| $75K | $58,040 | $57,984 | −$56 | Idaho |
| $100K | $74,540 | $74,465 | −$75 | Idaho |
| $150K | $106,921 | $106,809 | −$113 | Idaho |
| $200K | $140,403 | $140,253 | −$150 | Idaho |
Idaho offers higher take-home pay at every salary level. Idaho's 5.8% top rate is more favorable than Montana's 5.9%. At $100K, the difference is $75/year — that’s $6/month.
However, cost of living matters. Idaho has a cost index of 95 while Montana is at 97. With similar costs of living, the tax difference is the main factor.