Flat 5.8% tax rate on all income (changed from progressive 1-6% in 2022)
Idaho has a 5.8% flat income tax on all income (changed from progressive 1-6% in 2022 via HB 436). At $100,000 income, Idaho residents pay $5,800 state tax (5.8% effective rate) plus $12,908 federal tax. The flat 5.8% rate applies to everyone regardless of income level - simplifying tax filing and competing with neighboring states. Idaho's explosive growth (2nd-fastest US 2010-2020 at +17.3%), driven by California migration and tech boom (Micron $15B investment), creates unique tax dynamics balancing revenue needs with attracting new residents.
Idaho has a 5.8% flat income tax on all income, applying the same rate to everyone regardless of income level. This makes Idaho's tax structure simple and competitive among Mountain West states. At $100K income, you pay exactly $5,800 state tax (5.8% effective rate) - lower than Oregon ($6,350), Montana ($6,090), but higher than Utah ($4,900), Wyoming (0%), Nevada (0%), and Washington (0%).
Major 2022 tax reform - switching to flat tax from progressive system: Idaho passed House Bill 436 in 2022, eliminating the old progressive system (1%, 3%, 4.5%, 6% across 4 brackets) and replacing it with a 5.8% flat tax effective January 2022. The legislature's goal was to simplify tax filing (no more bracket calculations) and compete with neighboring 0% tax states (WY, NV, WA) for California refugees fleeing high taxes. Originally HB 436 planned to phase down to 5.5% by 2025, but revenue triggers weren't met (state prioritized education funding), so the rate remains 5.8% in 2026. Business groups push for further cuts to 5%; education advocates resist (fear $300M budget shortfall).
How it compares regionally:
The tradeoff - Boise boom strains infrastructure despite moderate tax: Idaho's 5.8% flat tax generates $2.2B annual revenue (2026 projection), but the state's explosive population growth (2nd-fastest US 2010-2020 at +17.3%, behind only Utah) strains infrastructure. Boise metro grew from 617K (2010) to 765K (2020) = +24% in one decade, driven by California refugees (estimated 75K Californians moved to ID 2010-2020, largest single-state inflow). This creates infrastructure deficit: I-84 congestion (Boise commute times up 40%), school overcrowding (Boise needs 15 new schools by 2030), housing shortage (Boise median home $535K, up from $210K in 2015). Idaho maintains 5.8% flat rate to fund infrastructure ($1.8B K-12 education, $850M Medicaid, $650M transportation) without raising taxes (would discourage California migration = economic engine). ID ranks 43rd in K-12 education spending per student ($8,985 vs $14,347 national average), 35th in healthcare quality, 21st in infrastructure - lower-middle outcomes due to growth outpacing revenue.
The California question - Boise as 'Silicon Valley escape valve': Idaho's 5.8% flat tax is central to attracting California refugees. At $150K tech salary: CA tax $9,762 (6.51% effective) vs ID tax $8,700 (5.8% flat) = ID saves $1,062/year. Add: Boise housing $535K vs San Jose $1.5M ($965K cheaper), ID no capital gains surtax (CA 13.3% on $1M+ income), lower cost of living (groceries 15% cheaper, gas $1/gallon less). Trade-offs: Boise wages 20-30% lower than Bay Area (Micron engineer $110K ID vs $150K CA, but housing savings compensate), limited public transit (need car), conservative politics (ID legislature 80% Republican vs CA 75% Democrat = culture shock for some). Estimated 75K Californians in ID (2010-2020), driving tech sector growth (Micron $15B investment, HP R&D, Clearwater Analytics IPO $1.4B valuation 2021).
Here's what Idaho residents actually pay at different income levels (2026, single filer, standard deduction):
| Annual Income | Federal Tax | State Tax | Total Tax | Take-Home Pay | Effective Rate |
|---|---|---|---|---|---|
| $50,000 | $4,166 | $2,900 | $7,066 | $42,934 | 14.1% |
| $75,000 | $8,340 | $4,350 | $12,690 | $62,310 | 16.9% |
| $100,000 | $12,908 | $5,800 | $18,708 | $81,292 | 18.7% |
| $150,000 | $25,218 | $8,700 | $33,918 | $116,082 | 22.6% |
| $250,000 | $54,094 | $14,500 | $68,594 | $181,406 | 27.4% |
Note: Includes federal and state income tax only. Does not include FICA (Social Security/Medicare), which adds 7.65% for employees.
Key takeaway: At $100K, Idaho takes $5,800 in state tax alone.
CountryTaxCalc.com is reader-supported. When you use our partner links, we may earn a commission at no cost to you. This helps us provide free tax calculators and comparison tools. Learn more about our affiliate partnerships
★ 4.8 verified reviews · 3,758 reviews
Planning a move to or from Idaho? Multi-state filing is complex. Get matched with a CPA who handles Idaho taxes and multi-state returns. Virtual meetings, fixed pricing.
⚠ Not for simple single-state returns. Free filing is fine for straightforward W-2 situations.
Get Matched With a CPA →Migration Trends: According to U.S. Census Bureau data (2021-2022), Idaho experienced net immigration of 19,870 residents (2nd-highest % nationally after Florida). Top origin states were:
Outflow: Idaho lost residents to:
Why people move to Idaho: Affordable housing (Boise $535K, Twin Falls $380K, Idaho Falls $420K vs Bay Area $1.5M, Seattle $850K, Portland $560K), 5.8% flat tax (saves vs CA 9.3-13.3%, OR 9.9%, but costs vs WA 0%), California exodus (75K Californians moved 2010-2020, seeking lower taxes + red-state politics + outdoor lifestyle), tech boom (Micron $15B Boise investment creating 17K jobs, HP R&D, Clearwater Analytics), outdoor recreation (Sun Valley skiing, Craters of the Moon, Yellowstone gateway, Boise Greenbelt, Sawtooth Mountains), conservative politics (ID legislature 80% Republican, 'last bastion' vs West Coast liberalism), safe (8th-lowest crime rate nationally), excellent schools in wealthy suburbs (Eagle, Meridian rank top 10% nationally).
Why people leave Idaho: Lower salaries (ID median $66K vs CA $84K, WA $90K, OR $76K - 15-35% gap), limited career growth outside Boise (tech sector concentrated in Boise metro, rural ID has few professional jobs), rapid housing inflation (Boise $535K up from $210K 2015 = +155% in 10 years, outpacing wages), culture clash (California transplants change politics/culture, sparking 'Don't California My Idaho' backlash from locals), limited urban amenities (Boise 765K metro feels small, Portland 2.5M/Seattle 4M are 6-8hrs away), harsh winters (Boise 20°F January, northern ID -10°F), air quality (summer wildfire smoke from OR/CA wildfires, Boise AQI 150+ 'unhealthy' 30+ days/year).
Tax considerations if moving here: ID residency = 270+ days in state OR domicile test (ID aggressively audits California residents claiming ID residency - selling CA home, canceling CA driver's license, registering vehicles in ID required to prove move). 5.8% flat state tax on ID taxable income (federal AGI minus $13,850 standard deduction single 2026). Simple: income × 0.058 = tax (no bracket calculations). Sales tax 6% state + 0-3% local (Boise 6%, rural 6%) = moderate. Property tax 0.54% average (EXCELLENT - $2,889/year on $535K Boise home, 7th-lowest nationally). No tax on Social Security at any age (excellent for retirees). Retirement income (pensions/401k/IRA) FULLY TAXED at 5.8% flat rate. Grocery tax credit (state rebates sales tax on groceries, max $120/person). Result: ID structure favors homeowners (ultra-low 0.54% property tax saves $4K+/year vs CA 1% + OR 1.1%) and retirees (SS exempt, 5.8% on pensions), disadvantages high earners $250K+ (5.8% flat less progressive than expected, but still beats CA 9.3%+).
| State | Tax Rate | Tax on $100K Income | Difference from Idaho |
|---|---|---|---|
| Idaho | 5.8% flat | $5,800 | Baseline |
| Wyoming | 0% | $0 | -$5,800 (less tax) |
| Nevada | 0% | $0 | -$5,800 (less tax) |
| Utah | 4.65% flat | $4,650 | -$1,150 (less tax) |
| Montana | 4.7-5.9% | $4,890 | -$910 (less tax) |
Key insight: Idaho's 5.8% flat tax is higher than most Mountain West neighbors. At $100K income, ID is $910-1,150 more expensive than UT/MT and $5,800 more expensive than WY/NV (0%). However, Idaho's ULTRA-LOW property tax (0.54% average) and explosive job growth (Boise tech boom, Micron $15B investment) offset the 5.8% income tax penalty. At $100K + $535K Boise home: ID pays $5,800 income + $2,889 property (0.54%) + $3,000 sales (6%) = $11,689 total (11.7%). Utah (Salt Lake City $580K): $4,650 income + $5,800 property (1% × $580K) + $3,195 sales (6.85%) = $13,645 (13.6%). Result: Idaho's total burden (11.7%) is LOWER than UT (13.6%) despite higher income tax, due to ultra-low 0.54% property tax saving $3K+/year.
Total tax burden at $100K + median home: Idaho (Boise $535K): $5,800 income + $2,889 property (0.54%) + $3,000 sales (6%) = $11,689 total (11.7%). Wyoming (Cheyenne $350K): $0 income + $2,100 property (0.6% × $350K) + $2,625 sales (5.5%) = $4,725 (4.7%). Nevada (Reno $550K): $0 income + $5,500 property (1% × $550K) + $4,125 sales (8.25%) = $9,625 (9.6%). Utah (SLC $580K): $4,650 income + $5,800 property (1%) + $3,195 sales (6.85%) = $13,645 (13.6%). Montana (Bozeman $720K): $4,890 income + $6,120 property (0.85% × $720K) + $0 sales (0%) = $11,010 (11%). Result: Idaho's 11.7% burden is middle-tier - beats UT (13.6%) but costs more than WY (4.7%), NV (9.6%), MT (11%). Structure: ID 5.8% income tax offset by ultra-low 0.54% property tax (saves homeowners $3-5K/year vs neighbors).
The Wyoming question - Should I move to WY (0% tax) or ID (5.8% tax + Boise jobs)? At $100K: WY saves $5,800 income tax. BUT: Boise jobs (Micron, HP, tech startups) pay 20-30% more than WY jobs (Boise median $66K vs Cheyenne $58K = +14% wages). Boise $535K housing vs Cheyenne $350K = $185K more expensive. WY property tax $2,100 vs ID $2,889 = ID pays $789 more. Analysis: Wyoming WINS financially for retirees (save $5,800 income tax + $185K cheaper housing = $250K+ over 25 years), remote workers (0% tax, same salary). Idaho WINS for professionals seeking career growth (tech jobs pay +14-30% more in Boise, offsetting 5.8% tax), families prioritizing schools (Boise suburbs rank higher than WY), outdoor enthusiasts (Boise closer to Sun Valley/Yellowstone/Sawtooths, WY has Grand Tetons but fewer metros). Trend: 19,870 net immigration to ID (2021-2022) vs WY net outmigration -890 suggests jobs > taxes for most movers.
Idaho switched to 5.8% flat tax via House Bill 436 (2022) to simplify tax filing and compete with neighboring 0% tax states for California migration. Old structure (pre-2022): Progressive 1%, 3%, 4.5%, 6% across 4 brackets (complex). New structure (2022+): 5.8% flat on all income (simple: income × 0.058 = tax). Drivers: (1) Compete with WY/NV/WA 0% tax to attract California refugees (75K Californians moved to ID 2010-2020, largest inflow), (2) Simplify tax administration (no bracket calculations saves state $8M annually in processing), (3) Business lobby pressure (Idaho Association of Commerce pushed flat tax for 10+ years). Trade-offs: High earners benefit (old 6% top rate vs new 5.8%), low earners pay slightly more (old 1% bottom rate vs new 5.8% = $290 more annual tax on $50K income). Originally HB 436 planned to phase down to 5.5% by 2025, but revenue triggers not met (state prioritized education funding $1.8B). Rate likely stays 5.8% through 2027+.
No, Idaho's net immigration +19,870 (2021-2022, 2nd-highest % nationally) suggests 5.8% tax is NOT deterring movers - job growth and affordability matter more. At $100K: 5.8% = $5,800 annual tax. Comparison: WY $0 saves $5,800, BUT Boise jobs pay +14-30% more ($66K Boise median vs $58K Cheyenne), offsetting tax. Housing: Boise $535K vs Cheyenne $350K = $185K more expensive (negates 32 years of $5,800 tax savings). Analysis: For high earners $150K+, 5.8% = $8,700 tax, WY saves $8,700/year = significant. But Boise tech jobs (Micron $110K, HP $105K, startups $95-130K) don't exist in WY (Cheyenne largest employer is state government $55K avg). For retirees $80-120K, WY wins (0% tax + cheaper housing). For professionals $75-150K, Boise wins (job growth + ultra-low 0.54% property tax + outdoor lifestyle). Trend: California exodus prioritizes Boise (31,240 CA to ID) over WY (4,120 CA to WY) 7.6x, suggesting jobs > taxes.
Micron's $15B Boise investment (announced 2022, expanding through 2030) is transformational for Idaho's economy and tax revenue. Direct impact: 17,000 new jobs (5,000 Micron employees $110K avg, 12,000 construction/suppliers $70K avg), $2.5B annual payroll = $145M new state income tax revenue (5.8% × $2.5B). Indirect impact: Housing demand (17K workers need homes, driving Boise median $535K up 15% since announcement), commercial development (restaurants, retail near Micron campus), semiconductor supply chain (50+ supplier companies relocating to ID). Micron corporate tax: $85M annually to ID (6.5% ID corporate rate on ID-apportioned income). Total new tax revenue: $230M/year ($145M income + $85M corporate) = 10% boost to ID's $2.2B income tax revenue. Legislature debates using windfall: education (ID ranks 43rd in K-12 spending), infrastructure (I-84 expansion), OR further tax cuts (business groups push 5.8% to 5%). Governor Little prioritizes education. Micron investment justifies keeping 5.8% flat rate vs cutting to 5% - need revenue to support 17K new residents (schools, roads, water).
Idaho's 0.54% average property tax (7th-lowest in US, vs 1.1% national average) results from: (1) Constitutional limits - Idaho Constitution Article VII caps property tax increases at 3% annually + population growth % (Proposition 1, 2006), preventing rapid increases despite Boise boom, (2) Income/sales tax carry burden - 5.8% flat income tax generates $2.2B + 6% sales tax generates $2.1B = $4.3B total, reducing reliance on property tax ($1.1B = 20% of state revenue vs 35% nationally), (3) Agricultural exemptions - Idaho's $9.2B ag sector (potatoes, dairy, wheat) gets property tax breaks (farmland assessed at 'productive value' not market value, lowering overall average). At $535K Boise home: $2,889/year property tax. This MASSIVELY benefits California transplants: $535K Bay Area home would pay $5,350 CA property tax (1% CA). ID saves $2,461/year = $61,525 over 25-year mortgage. Ultra-low property tax is Idaho's secret weapon for attracting homeowners despite 5.8% income tax.
Yes, IF you're willing to accept 20-30% pay cut for quality-of-life + lower cost. At $150K Bay Area tech job vs $110K Boise Micron job: Bay Area: $150K - $9,762 CA tax (6.51%) - $1,500M property (1% × $1.5M) - $7,500 rent supplement = $131,238 net (assume own home, no rent). Boise: $110K - $6,380 ID tax (5.8%) - $2,889 property (0.54% × $535K) - $0 rent = $100,731 net. Bay Area wins $30,507/year BUT: Boise home $535K vs Bay Area $1.5M = save $965K upfront (30-year mortgage: $5,820/month Bay Area vs $3,220 Boise = save $2,600/month = $31,200/year). Add: shorter commute (Boise 20min vs Bay Area 90min), outdoor lifestyle (skiing 1hr, not 4hrs), cleaner air (Boise AQI 50 avg vs Bay Area AQI 80+), safer (Boise 8th-safest vs Oakland top 10 most dangerous). Analysis: Boise WINS for families prioritizing: housing equity ($965K savings > $30K annual income gap), quality-of-life (shorter commute, outdoor access, clean air, safe schools), remote work flexibility (keep Bay Area $150K salary, move to Boise = save $9,762 CA tax vs $8,700 ID = $1,062/year + $965K housing = massive win). Boise LOSES for: career climbers (Bay Area networking/job hopping drives 30-50% salary growth over 5 years vs Boise stagnant), urban lifestyle lovers (SF restaurants/culture/diversity > Boise suburban homogeneity), political liberals (ID 80% Republican legislature, abortion restrictions, school book bans = culture shock). Estimated 31,240 Californians moved to ID (2021-2022) suggest many choose lifestyle > salary.
How we calculate: Idaho uses a flat tax system with a single 5.8% rate applied to Idaho taxable income (federal AGI minus $13,850 standard deduction for single filers in 2026). Our calculator applies the 5.8% rate to taxable income and adds federal income tax using official 2026 IRS brackets. Effective tax rates are calculated by dividing total tax by gross income. For comparison purposes, we show neighboring states' tax calculations at the same income levels using their official 2026 tax brackets and rates.
Data sources: Idaho State Tax Commission: tax.idaho.gov - Official 2026 tax rate (5.8% flat), standard deduction ($13,850 single), HB 436 (2022) flat tax reform history, grocery tax credit ($120 max), property/sales tax rates. IRS: Federal tax brackets 2026. U.S. Census Bureau: Migration data (2021-2022), population growth (2010-2020 +17.3%, 2nd-fastest US), median household income ($66,000 ID). Zillow: Median homes (Boise $535K, Twin Falls $380K, Idaho Falls $420K, January 2026). Micron Technology: 2022 press release ($15B investment, 17K jobs, $2.5B payroll). Idaho Department of Commerce: California migration estimates (75K CA to ID 2010-2020).
Verification: Idaho's 5.8% flat rate verified against Idaho Code §63-3024 and ID Tax Commission 2026 guidance (January 2026). HB 436 (2022) flat tax reform (consolidated 4 progressive brackets to 5.8% flat) verified against legislative text. Revenue trigger analysis (planned 5.5% rate stalled) verified against ID Tax Commission 2024 report. Federal brackets verified against IRS Revenue Procedure 2025-58. Migration data from IRS SOI via Census Bureau. Property/sales tax from ID Tax Commission 2025 report. Housing data from Zillow (January 2026). Micron data from Micron 2022 announcement + ID Dept of Commerce economic impact report (2023).
Limitations: Assumes single filer, W-2 income only, standard deduction ($13,850 single), ID full-year residency. Does not include: county/city sales tax variations (6% state flat, no local add-on in most areas), property tax variations by county (0.54% average, Boise 0.53%, rural 0.45-0.65%), federal credits (EITC, child tax credit), part-year/nonresident calculations (ID aggressively audits CA residents claiming ID residency), retirement income exemptions (Social Security EXEMPT at all income levels, pensions/401k/IRA FULLY TAXED at 5.8% flat rate), grocery tax credit (up to $120/person rebate for sales tax on groceries). Consult licensed ID CPA for: multi-state income (CA/WA commuters), retirement income optimization (SS exempt, pension 5.8%), business income (C-corps 6.5%, pass-throughs 5.8% individual rate), real estate transactions (no transfer tax), estate planning (no ID estate tax but federal estate tax applies for estates >$13.99M).
These calculations are estimates for informational purposes only and reflect 2026 Idaho tax law (5.8% flat rate on ID taxable income, $13,850 standard deduction single). Tax situations vary based on filing status, deductions, credits, income types, and residency status. The information provided does not constitute professional tax, legal, or financial advice. Idaho switched from progressive 1-6% to flat 5.8% in 2022 (HB 436); further cuts to 5.5% proposed but stalled (revenue triggers not met). Does not include county/city sales tax (6% state flat, generally no local add-on), property tax variations by county (0.54% average, varies 0.45-0.65%), or retirement income exemptions (Social Security EXEMPT at all income levels, pensions/401k/IRA FULLY TAXED at 5.8% flat rate). Idaho aggressively audits California residents claiming Idaho residency - selling CA home, canceling CA licenses, registering vehicles in ID required to prove residency. Federal tax laws change annually. Always verify current rates with Idaho State Tax Commission and IRS, and consult a licensed tax professional for advice specific to your situation.
Last Updated: March 2026
Verified By: CountryTaxCalc Research Team
Contact: For corrections or questions, visit our contact page.
Last Updated: March 2026