Idaho simplified to a flat 5.8% income tax in 2023 — and Boise has been one of the fastest-growing cities in the US for the past decade.
Idaho uses federal taxable income as a close starting point, meaning the $16,100 federal standard deduction (single) flows through to your Idaho return. No Idaho city levies a local income tax. Idaho exempts Social Security from state income tax for most retirees and has been a destination for California and Washington transplants — though both of those states offer lower income tax burden at different income levels.
Boise has consistently ranked among the fastest-growing cities in the United States over the past decade, driven by migration from California, Washington, and the Bay Area. Micron Technology (Boise's largest private employer and one of the only US memory chip manufacturers), Hewlett Packard, and a growing technology ecosystem have brought high-paying tech jobs. The median household income in Ada County (Boise metro) has risen significantly — which makes Idaho's 5.8% flat income tax increasingly relevant for new arrivals used to paying zero state income tax in Washington.
The California migrant's calculation is nuanced. A tech worker moving from California to Boise might be comparing 9.3%+ California tax vs. Idaho's 5.8% flat rate — a meaningful savings. But workers coming from Washington state (0% income tax) are moving to a higher-tax environment. At $120,000, a Washington-to-Boise move costs approximately $5,800 per year in new state income tax. Many migrants accept this trade-off given Boise's lower housing costs (historically), but the tax difference is real and should factor into salary negotiations when moving.
Idaho's 2023 tax reform simplified from graduated brackets to a flat rate. Prior to 2023, Idaho had multiple brackets with a top rate of 6%. The 2023 reform compressed the system to a single 5.8% flat rate. This simplified withholding calculations and gave Idaho a more competitive rate for high earners who were previously in the top bracket. The flat rate means every additional dollar earned is taxed at the same rate — there's no bracket cliff to plan around.
Idaho's Treasure Valley (Boise, Nampa, Meridian, Caldwell) has become one of the most competitive housing markets in the intermountain West. The rapid population growth that made Boise famous has also pushed housing costs up substantially from their 2019 lows — though they remain far below San Francisco or Seattle levels. For workers considering Idaho, the total financial picture includes the income tax, housing costs, and cost of living — all of which have shifted significantly over the past five years.
Estimates only. Idaho flat 5.8% on federal taxable income (federal standard deduction applies). Consult a tax professional for advice.
| Gross Pay (this check) | $0.00 |
| Federal Income Tax | −$0.00 |
| Idaho State Tax (flat 5.8%) | −$0.00 |
| Social Security (6.2%) | −$0.00 |
| Medicare (1.45%) | −$0.00 |
| Net Take-Home Pay | $0.00 |
Idaho has a flat 5.8% income tax rate for 2026, enacted as part of the 2023 tax reform that simplified Idaho from a six-bracket system. Idaho uses federal taxable income as its base, so the federal standard deduction ($16,100 single / $32,200 married for 2026) reduces Idaho taxable income. No Idaho city adds a local income tax.
Washington has no state income tax. At $100,000 in salary, Idaho's 5.8% flat rate costs about $4,800 per year more than Washington. For workers considering Boise vs. Spokane (just across the Washington border) or the Lewiston/Clarkston area, the income tax difference is meaningful. Spokane offers Washington's 0% income tax while remaining geographically close to Idaho markets.
Idaho does not tax Social Security benefits for most retirees. Idaho follows federal rules for Social Security taxation in many cases, and the state provides deductions that effectively exempt Social Security for lower- and middle-income retirees. Higher-income retirees may owe some Idaho tax on a portion of Social Security — verify with an Idaho tax professional if your combined income is high.
Boise's growth was driven by California and Seattle transplants fleeing high housing costs, combined with major tech employers (Micron Technology, HP Inc., and growing remote-work opportunities). This migration brought higher salaries that interact more significantly with Idaho's 5.8% flat rate. A California tech worker moving to Boise and earning $150,000 saves roughly $5,000+ per year on state income tax compared to California — but pays $8,700 more than if they had moved to Nevada or Washington instead.
On $80,000 (single, biweekly), Idaho withholds approximately $161–$172 per paycheck in state income tax — roughly $4,175–$4,450 annually. The effective rate is about 5.2–5.6% on gross pay, since the $16,100 standard deduction reduces taxable income to about $63,900, and 5.8% of $63,900 is $3,706. Exact withholding will vary based on W-4 elections.
No. Boise, Nampa, Meridian, Idaho Falls, Pocatello, Coeur d'Alene, and all other Idaho municipalities do not levy local income taxes on wages. Workers pay only Idaho's flat 5.8% state rate with no city surcharge of any kind.
Idaho taxes overtime and tips at the regular 5.8% flat state rate. The federal exemptions under the One Big Beautiful Bill apply only to federal income tax — Idaho has not enacted state-level equivalents. See our Overtime Tax Calculator for your federal savings on overtime.
Idaho has discussed further tax cuts following the 2023 reform that established the 5.8% flat rate. However, unlike Iowa and West Virginia, Idaho has not yet enacted automatic revenue-trigger reductions. Whether the rate goes below 5.8% depends on future legislative action and state revenue performance. Watch Idaho State Tax Commission and legislature announcements for updates.