Idaho income tax calculator 2026
This page provides an estimate of Idaho state income tax under the current published tax structure using the Idaho individual income tax rate structure administered by the Idaho State Tax Commission. The estimate is based on Idaho taxable income and the official flat-rate worksheet thresholds and rate that apply under the current statutory structure.
Estimates are shown for the 2026 tax year. In cases where official figures have not yet been finalized, calculations are based on the most recently available data and may be updated when final guidance is published.
Annual taxable income for the selected tax year.
Estimated state income tax
Shows an estimated state income tax and an effective rate based on the provided values.
Idaho income tax calculator 2026 – how it works
Idaho imposes a state individual income tax using a flat-rate worksheet structure. Under the current published Idaho tax structure, Idaho applies a 0% rate to Idaho taxable income up to 4,811 for single filers and married filing separately, and applies a 5.3% rate to taxable income above that threshold. This calculator estimates Idaho state income tax by applying the worksheet method published in the official Idaho Form 40 instructions. If taxable income does not exceed the threshold, the estimated tax is zero. If taxable income exceeds the threshold, the excess amount above 4,811 is multiplied by 5.3%. Official authority: Idaho State Tax Commission. The worksheet thresholds and rate are documented in the Idaho Individual Income Tax Rate Schedule and the current Form 40 instructions.
Examples
Example 1 (Idaho taxable income: 4,000). Because 4,000 is at or below the worksheet threshold, the estimated Idaho tax is 0. Example 2 (Idaho taxable income: 6,000). The amount above the threshold is 1,189 (6,000 minus 4,811). Applying the 5.3% rate produces an estimated tax of 63.02. Example 3 (Idaho taxable income: 50,000). The amount above the threshold is 45,189 (50,000 minus 4,811). Applying the 5.3% rate produces an estimated tax of 2,395.02. These examples illustrate how the Idaho worksheet applies the flat rate only to the portion of taxable income above the threshold.
Limitations and important notes
This estimate is limited to a single calculation model: Single and Married Filing Separately. Idaho publishes a different threshold for Married Filing Jointly, Head of Household, and Qualifying Surviving Spouse, which are not supported by this calculator. This calculator estimates tax on Idaho taxable income only. It does not compute Idaho taxable income from federal adjusted gross income, Idaho additions or subtractions, standard or itemized deductions, credits, or other Idaho-specific adjustments. Idaho income tax law includes additional rules and administrative guidance that may affect individual situations. For authoritative details, rely on official Idaho State Tax Commission publications and Form 40 instructions.
FAQs about Idaho income tax calculator 2026
What Idaho income tax rate applies?
Under the current published Idaho tax structure, Idaho applies a 0% rate to taxable income up to 4,811 for single filers and married filing separately, and a 5.3% rate to taxable income above that threshold. These amounts are published by the Idaho State Tax Commission.
Does Idaho use different thresholds for married filing jointly?
Yes. Idaho uses a higher worksheet threshold for Married Filing Jointly, Head of Household, and Qualifying Surviving Spouse. This calculator does not implement those filing statuses.
What income does this Idaho tax estimate use?
This estimate uses Idaho taxable income as reported on Idaho Form 40, line 19. It does not derive taxable income from federal adjusted gross income or apply Idaho-specific deductions or credits.
Which official source documents Idaho’s tax rate?
The Idaho State Tax Commission publishes the official rate and thresholds in the Individual Income Tax Rate Schedule and the Form 40 instructions.
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Calculations are simplified and for guidance only. Always double-check results and current rules with official sources or a qualified professional before making financial decisions.