A Mechanical Engineer earning $120K/year in Idaho takes home $86,835 after all taxes. That’s $7,236/month, with an effective tax rate of 27.6%.
The estimated median salary for Mechanical Engineers in Idaho is $87K (adjusted from the national median of $92K using Idaho’s cost-of-living index of 95). At $120K, you’re earning 38% above the state-adjusted median for this profession.
This salary places you in the upper tier for Mechanical Engineers in Idaho, likely reflecting senior-level experience, specialized skills, or management responsibilities. At this level, tax optimization becomes increasingly important — the difference between the best and worst states at $120K is $10,374/year.
Filing as married filing jointly on $120K (single earner) saves you $7,585/year ($632/month) compared to filing single. This marriage bonus comes from the doubled standard deduction ($32,200 vs $16,100) and wider lower brackets.
Mechanical engineers who hold a Professional Engineer (PE) license can deduct licensing and continuing education costs if self-employed. Patent bonuses or invention awards from your employer are taxed as ordinary income. Engineers who travel to job sites or manufacturing facilities should track mileage if self-employed — the 2026 standard mileage rate can add up to significant deductions. If you receive a signing bonus when changing employers, it’s withheld at the 22% supplemental rate regardless of your actual bracket.
At #41 out of 50 states for take-home pay on a $120K salary, Idaho is one of the highest-tax states at this salary level. You’d keep $6,360 more per year in Alaska (#1), or $530/month.
After adjusting for cost of living, Idaho ranks #30 in purchasing power. That’s a boost from #41 in raw take-home — Idaho’s lower costs stretch your paycheck further.