Filing and paying Idaho income tax
- Return
- Form 40 for residents, due April 15, with the $10 permanent building fund tax on line 31.
- Withholding
- The Tax Commission revised its 2026 withholding tables in July 2026 after the child tax credit expired.
To see how Idaho sits against every other state on top rate, bracket count and standard deduction, see state income tax rates for 2026 — all 51 jurisdictions in one sortable table.
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) | $4,202 | $17,372 | — |
| Washington | $0 | $13,170 | -$4,202 |
| Oregon | $7,148 | $20,318 | +$2,946 |
| Nevada | $0 | $13,170 | -$4,202 |
| Utah | $4,450 | $17,620 | +$248 |
| Wyoming | $0 | $13,170 | -$4,202 |
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 taxable income above the first $4,811, which is taxed at 0% (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 $4,202 in Idaho state income tax — for a total income tax of about $17,372, an effective rate of 17.4%. This excludes FICA (Social Security and Medicare), which adds roughly 7.65% on top.
What is the Idaho income tax rate for 2026?
5.3% on taxable income above the zero-rate threshold, the same as 2025.
Is the Idaho child tax credit gone?
Yes. The $205 per-child credit applied only to tax years beginning before January 1, 2026.
What is the Idaho permanent building fund tax?
A flat $10 added to the Idaho return of anyone required to file, unless they are blind or receiving Idaho public assistance.
Does Idaho tax Social Security?
No. Social Security benefits included in federal income are subtracted on the Idaho return.
For the preferential federal rates on long-term gains, see the Capital Gains Tax Calculator. For the federal brackets, standard deduction, and Social Security wage base that sit underneath this state calculation, see 2026 Tax Calculators.