How Paycheck Taxes Work in Idaho
How paycheck taxes work in Idaho: Your employer withholds federal income tax based on your W-4, then Idaho state income tax using state withholding tables. Social Security (6.2%) and Medicare (1.45%) are also deducted from each paycheck. Idaho's shift to a flat tax simplifies the calculation for residents, ensuring a consistent 5.8% withholding regardless of income level. Taxable income is generally determined by taking the Federal Adjusted Gross Income (AGI) and subtracting state-specific deductions. This flat-rate system makes payroll budgeting more predictable for employees and employers alike across the state.
Idaho State Tax Information
Idaho has moved to a flat state income tax system, applying a 5.8% rate to all taxable income for 2026.
Idaho's shift to a flat tax simplifies the calculation for residents, ensuring a consistent 5.8% withholding regardless of income level. Taxable income is generally determined by taking the Federal Adjusted Gross Income (AGI) and subtracting state-specific deductions. This flat-rate system makes payroll budgeting more predictable for employees and employers alike across the state.
Idaho is a better state to model carefully when you are comparing job offers, relocations, or remote-work options because state withholding can materially change annual take-home pay.
Federal Income Tax
Federal income tax uses progressive brackets: higher income is taxed at higher rates, not all at one rate. The standard deduction reduces taxable income before brackets apply, and your W-4 affects how much is withheld through the year.
Social Security
Social Security tax (FICA) is 6.2% of wages up to the annual wage base ($184,500 in 2026). Both employee and employer pay this amount; this calculator shows the employee portion.
Medicare
Medicare tax is 1.45% on all wages with no cap. High earners pay an additional 0.9% on wages above $200,000 (single) or $250,000 (married filing jointly).