How Idaho Income Tax Works
Idaho uses a flat income tax rate of 5.3% for 2026. Every dollar of taxable income above the standard deduction is taxed at the same state rate. Federal income tax still uses the seven-bracket 10%–37% progressive system on top of state.
Idaho moved from a graduated tax to a flat rate in 2023. The rate has stepped down each year since — 5.695% in 2025, then 5.30% in 2026 — making it one of the simpler and increasingly competitive state tax codes in the West.
Idaho Job Market & Income Context
Agriculture (potatoes), tech (Micron HQ in Boise), and outdoor recreation drive the economy; rapid growth from California migration.
How Idaho Income Tax Compares to Neighboring States
Total income tax (federal + state) on a $100,000 annual salary in 2026, single filer using the standard deduction:
| State | State Tax | Total Income Tax | vs. Idaho |
|---|---|---|---|
| Idaho (here) | $4,505 | $17,675 | — |
| Washington | $0 | $13,170 | -$4,505 |
| Oregon | $8,196 | $21,366 | +$3,691 |
| Nevada | $0 | $13,170 | -$4,505 |
| Utah | $4,550 | $17,720 | +$45 |
| Wyoming | $0 | $13,170 | -$4,505 |
A negative "vs." figure means that state collects less total income tax than Idaho. Federal portion is identical across states; only state tax varies.
Frequently Asked Questions
What is the Idaho state income tax rate for 2026?
Idaho has a flat 5.3% state income tax rate for 2026. The rate is the same regardless of income — applied to your taxable income after the standard deduction. Federal rates (10%–37%) layer on top.
How much income tax will I pay in Idaho on a $100,000 salary?
For a single filer earning $100,000 in Idaho in 2026, expect approximately $13,170 in federal income tax and $4,505 in Idaho state income tax — for a total income tax of about $17,675, an effective rate of 17.7%. This excludes FICA (Social Security and Medicare), which adds roughly 7.65% on top.
What's the difference between effective and marginal tax rate?
Your marginal rate is the rate applied to your last dollar of taxable income — the bracket your top dollar lands in. Your effective rate is your total income tax divided by your total income — the average rate across everything you earned. Effective is always lower than marginal because lower brackets cover the first portions of your income at lower rates.
Does Idaho tax retirement income, Social Security, or capital gains?
Federal rules: long-term capital gains use preferential rates (0%, 15%, 20%) — see our Capital Gains Tax Calculator. Social Security is taxable federally if your combined income exceeds certain thresholds. Idaho's treatment of retirement income, Social Security, and capital gains varies — many states fully or partially exempt Social Security, and some provide pension exclusions. Consult Idaho's Department of Revenue for specifics.
How is this Idaho income tax estimate calculated?
We apply the 2026 federal IRS tax tables (10%–37% across seven brackets) and Idaho's 2026 state tax schedule to your taxable income (gross income minus the standard deduction). The calculator handles wages, self-employment income (with SE tax and the deductible half), and other income; you can also switch to itemized deductions. Tax credits, AMT, and preferential capital gains rates are not modeled — this is an estimate of ordinary income tax only.