Free Idaho (ID) income tax calculator with 2026-specific rates. Calculate your exact income tax using real Idaho data.
Idaho has a top marginal income tax rate of 5.8%. The state uses a flat tax rate on all taxable income.
Idaho uses a flat income tax rate of 5.8% on all taxable income.
Idaho residents must file a state income tax return with the Idaho Department of Revenue (or equivalent agency). Most taxpayers can file electronically. The deadline typically aligns with the federal tax deadline of April 15.