Side-by-side tax comparison between Colorado (4.4% top rate, flat) and Idaho (5.3% top rate, flat). See which state lets you keep more at every salary level, and how cost of living changes the picture.
Colorado uses a flat income tax (4.4% flat) while Idaho has a flat system (5.3% flat). On a $100K salary, Colorado takes $4,400 in state and local taxes compared to Idaho’s $5,300 \u2014 a difference of $900.
Both states use flat brackets, but Idaho’s top rate of 5.3% is higher than Colorado’s 4.4%.
Colorado wins at 10 out of 10 salary levels tested. The advantage exists but is modest across the income spectrum.
| Salary | Colorado | Idaho | Difference | Winner |
|---|---|---|---|---|
| $40K | $32,560 | $32,200 | −$360 | Colorado |
| $50K | $40,155 | $39,705 | −$450 | Colorado |
| $60K | $47,750 | $47,210 | −$540 | Colorado |
| $75K | $58,238 | $57,563 | −$675 | Colorado |
| $100K | $74,725 | $73,825 | −$900 | Colorado |
| $120K | $87,915 | $86,835 | −$1,080 | Colorado |
| $150K | $107,151 | $105,801 | −$1,350 | Colorado |
| $200K | $140,087 | $138,287 | −$1,800 | Colorado |
| $250K | $172,264 | $170,014 | −$2,250 | Colorado |
| $300K | $202,129 | $199,429 | −$2,700 | Colorado |
Take-home pay only tells part of the story. Colorado has a cost of living index of 105 while Idaho is at 95 (national average = 100).
The cost of living gap is moderate. After adjustment, $100K has purchasing power of $71,167 in Colorado vs $77,711 in Idaho. However, Idaho actually provides better purchasing power despite Colorado’s take-home advantage.
For a single earner at $100K filing jointly, take-home becomes $80,310 in Colorado and $79,410 in Idaho \u2014 a difference of $900. The gap remains similar regardless of filing status.
On paper, moving from Idaho to Colorado would save $900/year on a $100K salary, or $4,500 over 5 years. But relocation involves real costs: moving expenses, potentially buying/selling a home, changing jobs, and adjusting to a new community.
At $900/year, the tax difference alone likely isn’t worth relocating for. Other factors — job market, lifestyle, family — should drive the decision. The tax savings are a nice bonus if you’re already considering the move for other reasons.