Idaho State Income Tax Guide (2026)

Scenario 1: St. Luke's Health bedside RN in Boise, $74,000

St. Luke's Health System is the largest healthcare employer in Idaho — Treasure Valley flagship plus regional hospitals across southern Idaho. Bedside nursing comp tracks Mountain-West-average ($70K–$85K floor RN), with $4–$8/hour shift differentials adding 14%–18% on nights and weekends. The combined Idaho + federal + payroll bill works out to about $590 per biweekly paycheck. A 1-bedroom in the North End or Hyde Park runs $1,300–$1,650; a 2BR in Meridian or Eagle runs $1,650–$2,100. The same nurse earning $74K in Portland pays roughly $5,800 in Oregon tax (vs Idaho's $2,860) and $400/month more for a comparable apartment. Idaho's net advantage at moderate income is real — about $7,500/year in combined tax-and-rent vs Portland — and the Front Country trail access from any Boise neighborhood is the lifestyle premium that drove the post-2020 migration.

Scenario 2: Micron mid-career semiconductor engineer in Meridian, $135,000

Micron Technology is the largest US-headquartered memory semiconductor company and the only major DRAM and NAND manufacturer with HQ in the United States. About 6,500 employees in Boise across HQ, R&D, and pilot fabrication, with the announced $15B fab expansion bringing roughly 2,000 additional jobs by 2030. Mid-career semiconductor engineering comp at Micron Boise tracks Bay Area pay scale at 75%–85% — base $125K–$165K, RSUs $30K–$60K, performance bonuses $15K–$25K. Total comp $180K–$245K is normal at senior-engineer levels. A 4-bedroom in Eagle, north Meridian, or northwest Boise runs $625K–$875K. Same square footage in Bay Area suburbs: $1.6M–$2.4M. The structural housing-and-tax advantage at $200K+ comp is one of the better arbitrages in semiconductor engineering. Trade-off: Boise's tech career mobility outside Micron + HP is genuinely thin, and the cost-of-living advantage that drove the post-2020 migration has narrowed considerably as housing has caught up.

Scenario 3: Idaho National Laboratory cleared nuclear engineer in Idaho Falls, $155,000 (Q clearance)

Idaho National Laboratory is operated by Battelle Energy Alliance on a Department of Energy contract. The actual engineering culture is closer to a federal-research lab than a private-sector reactor vendor — substantial autonomy, multi-year project arcs, security clearances that take 12–18 months and become a real barrier to job-hopping. Q clearance is the entry exam to the INL middle class. Cleared nuclear engineering pay tracks DOE national-lab scales similar to Sandia or Oak Ridge. A 4-bedroom in Idaho Falls or Ammon runs $325K–$475K — well below equivalent housing in any peer national-lab city (Albuquerque, Knoxville, Livermore). Idaho Falls is small (population ~65K) and the local lifestyle is rural-leaning, but for nuclear-track scientists who value federal-employment stability and project depth, the math is favorable.

Q: I'm thinking about moving from California to Boise for the cost of living. Is the math still working?

Less dramatically than in 2020–2022, but yes if you compare to expensive California metros. California top combined at $200K runs roughly 9.3% effective; Idaho 4.4%. Income tax delta: about $9,800/year. Boise housing has appreciated dramatically (median ~doubled 2019–2024), narrowing the housing-cost arbitrage — a 4-bedroom in Eagle or northwest Boise runs $625K–$875K vs $1.6M–$2.4M in Bay Area suburbs. The arbitrage is real but narrower than the migration narrative suggests; for migrants from Inland Empire or Sacramento (where housing is closer to Boise's) the gap is smaller and worth running carefully.

Q: What about the Coeur d'Alene / Spokane cross-border math?

Coeur d'Alene (Idaho, Kootenai County) and Spokane (Washington, Spokane County) sit 30 miles apart across the state line. Idaho residents working in Spokane owe Idaho tax on the wage income (Idaho taxes residents on worldwide income); Washington has no income tax to offset against. Washington residents working in Coeur d'Alene owe Idaho tax on the Idaho-source wages and file an Idaho non-resident return. There's no reciprocity. The post-2020 migration into Coeur d'Alene from Washington was driven mostly by lifestyle (lower cost, smaller-town feel), not tax — Washington W-2 earners moving to Coeur d'Alene actually pay MORE in tax (Idaho 5.3% vs Washington 0% on wages).

Q: Is INL pay competitive with private-sector nuclear engineering?

Comparable, with a meaningful cost-of-living advantage. Cleared mid-career nuclear engineer at INL: $130K–$170K base plus 5%–6% match plus 401(k) Mega Backdoor Roth space. Same role at Westinghouse, GE Hitachi, or NuScale's Portland office: $135K–$185K base. The private-sector role pays $5K–$15K more in base but Idaho Falls housing is half the cost of any peer national-lab city. Net-net INL wins on take-home by $20K–$35K/year, plus federal-employment stability and the deeper-physics project work. Trade-off is geographic isolation — Idaho Falls is genuinely small.

Q: Does Idaho tax Social Security or pensions?

Social Security is fully exempt at the state level. Pensions (private and public), 401(k) and IRA distributions, and capital gains from retirement-account withdrawals are all taxed at the flat 5.3% rate. Military retirement up to 100% exempt for retirees age 65+ or 62+ with disability rating; partial exemption otherwise. The senior Circuit Breaker on property tax adds up to $1,500/year reduction for income-qualified retirees. For paid-off-mortgage retirees at moderate income, the combined Idaho retirement math is favorable — better than Utah on Social Security treatment, comparable to most Mountain West peers on combined burden.

Q: Will rates keep dropping?

Maybe. Five years, four cuts (7.4% → 6.5% → 6.0% → 5.3% flat). The legislature has signaled appetite for further reduction if revenue allows, and the 2025 session debated 5.0% but tabled it. Plan around 5.3% as the durable rate; treat any further cut as upside.