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Tax year 2026

Idaho vs Washington Income Tax — 2026

A single filer earning $100,000 pays $4,447 less per year in Washington than in Idaho — $371 a month. Idaho charges $4,447; Washington charges $0.

Why this pair has a page: bordering states.

Idaho at $100K
$4,447
4.45%
Washington at $100K
$0
0.00%
Annual difference
$4,447
$371 a month
National ranks
37 vs 8
of 50, lowest tax first

The bill at every income

Single filer, standard deduction, no dependents. State income tax only.

Idaho and Washington income tax compared at seven income levels, 2026
Gross incomeIdaho taxWashington taxDifference
$50,000$1,797$0$1,797 less in WA
$75,000$3,122$0$3,122 less in WA
$100,000$4,447$0$4,447 less in WA
$150,000$7,097$0$7,097 less in WA
$250,000$12,397$0$12,397 less in WA
$500,000$25,647$0$25,647 less in WA
$1,000,000$52,147$0$52,147 less in WA
Annual state income tax, Idaho versus Washington
ID at $50,000: $1,797ID at $50,000$1,797WA at $50,000: $0WA at $50,000$0ID at $75,000: $3,122ID at $75,000$3,122WA at $75,000: $0WA at $75,000$0ID at $100,000: $4,447ID at $100,000$4,447WA at $100,000: $0WA at $100,000$0ID at $150,000: $7,097ID at $150,000$7,097WA at $150,000: $0WA at $150,000$0ID at $250,000: $12,397ID at $250,000$12,397WA at $250,000: $0WA at $250,000$0ID at $500,000: $25,647ID at $500,000$25,647WA at $500,000: $0WA at $500,000$0ID at $1,000,000: $52,147ID at $1,000,000$52,147WA at $1,000,000: $0WA at $1,000,000$0

How the two systems differ

Idaho and Washington income tax systems compared
IdahoWashington
Tax structureFlat rateNo income tax
Top marginal rate5.3%None
Number of brackets1—
Standard deduction (single)$16,100—
Personal exemptionNone—
Local income taxesNoNo
Capital gainspreferentialseparate
Population (2024)2,001,6197,958,180

By filing status

Idaho and Washington tax on $100,000 by filing status, 2026
Filing statusIdahoWashingtonDifference
Single$4,447$0$4,447 less in WA
Married filing jointly$3,593$0$3,593 less in WA
Married filing separately$4,447$0$4,447 less in WA
Head of household$4,020$0$4,020 less in WA

Change the assumptions

Adjust income and filing status, or swap either state. The URL updates so you can share the exact comparison.

At $100,000 as a single filer, Washington costs $4,447 less per year than Idaho — $371 a month.

Idaho compared with Washington at $100,000
IdahoWashingtonDifference
State income tax$4,447$0$4,447
Per month$371$0$371
Effective rate4.45%0.00%4.45 pts
Marginal rate5.3%None5.30 pts
Standard deduction$16,100—$16,100
Taxable income$83,900—$83,900
Tax structureFlat rateNo income tax
Local income taxesNoNo

Full detail: Idaho · Washington · methodology

What this comparison leaves out

Sources for both states

  1. 1.Idaho State Tax CommissionState revenue department
    Table for Percentage Computation Method of Withholding (EPB00744, 07-23-2026)
    https://tax.idaho.gov/document-mngr/pubs_EPB00744/
    Retrieved · Annual payroll period: single/head of household, "5.3% of the amount over $16,100"; married, "5.3% of the amount over $32,200" - i.e. the 5.3% rate applied above the 2026 federal standard deduction.
  2. 2.Washington State Department of RevenueState revenue department
    Income tax
    https://dor.wa.gov/taxes-rates/income-tax
    Retrieved
  3. 3.Tax FoundationResearch organisation (cross-check)
    State Individual Income Tax Rates and Brackets, 2026
    https://taxfoundation.org/data/all/state/state-income-tax-rates-2026/
    Retrieved · Lists Washington as taxing capital gains income only.

Figures on this page were last checked against these sources on . Found something wrong? Report it.