Idaho’s income tax rate is a flat 5.3% on individual taxable income. The rate applies only to income above a zero-rate threshold of $2,500 for single and head-of-individual filers, and $5,000 for married couples filing jointly, surviving spouses, and heads of household.1Idaho State Legislature. Idaho Code 63-3024 – Individuals Tax and Tax on Estates and Trusts Anything below those thresholds is taxed at zero. The flat system replaced Idaho’s old graduated brackets, which once ran from 1% up to 6.925% depending on the income slice.
How the Flat Rate Actually Hits Your Income
The 5.3% rate does not apply to your gross paycheck. Idaho begins with your federal adjusted gross income, applies its own additions and subtractions, lets you take a standard deduction (or itemize), and only then taxes what is left above the zero-rate threshold.
A rough example: a single filer with $30,000 in gross income subtracts the standard deduction first. Idaho uses the same standard deduction as the federal government, which for 2026 returns is expected to run around $16,100 for single filers and $32,200 for married couples filing jointly. Of the income that survives that deduction, only the portion above $2,500 is taxed, and it is taxed at 5.3%. Head-of-household filers get the $5,000 threshold, not the $2,500 one, which is easy to miss.
What Idaho Lets You Subtract Before Applying the Rate
Several Idaho-specific subtractions can meaningfully shrink the income that reaches the 5.3% rate.
- Social Security and railroad retirement benefits that were included in your federal taxable income come back out on the Idaho return. Idaho does not tax Social Security.2Idaho State Legislature. Idaho Code 63-3022 – Computation of Taxable Income for Idaho
- Contributions to Idaho’s IDeal 529 college savings plan are deductible up to $6,000 per year for individuals and $12,000 for married couples filing jointly. Non-education withdrawals may have to be added back.2Idaho State Legislature. Idaho Code 63-3022 – Computation of Taxable Income for Idaho
- Active-duty service members can subtract military compensation for service performed outside Idaho, provided the duty was continuous for at least 120 days.2Idaho State Legislature. Idaho Code 63-3022 – Computation of Taxable Income for Idaho
The common addition cuts the other way. If you itemized on your federal return and deducted state or local income taxes, Idaho makes you add that amount back before calculating Idaho tax.2Idaho State Legislature. Idaho Code 63-3022 – Computation of Taxable Income for Idaho
Credits That Reduce What You Owe at 5.3%
Grocery Tax Credit
Idaho’s grocery credit is $155 per person for tax year 2025 and beyond. You claim $155 for yourself, $155 for your spouse, and $155 for each qualifying dependent, so a family of four receives $620.3Idaho State Legislature. Idaho Code 63-3024A – Food Tax Credits and Refunds The credit is fully refundable, so if it exceeds your tax, Idaho pays you the difference. Residents who are not required to file a return can still claim it on a separate form. The credit is reduced for months when a household member received SNAP benefits or was incarcerated, and part-year residents receive a prorated amount.
Parental Choice Tax Credit
Full-time Idaho residents with K-12 students aged 5 to 18 can claim up to $5,000 per eligible student for qualifying education expenses, or up to $7,500 per student with a qualifying disability. The credit is refundable.4My School Choice. About the Program
Whether the Idaho Rate Applies to You
Full-year Idaho residents pay the 5.3% rate on income from every source, including wages earned in other states. When another state taxes the same income, Idaho allows a credit to prevent double taxation. Part-year residents pay on income earned while living in Idaho plus any Idaho-source income earned after moving away. Nonresidents pay only on Idaho-source income.5Idaho State Tax Commission. Idaho Residency Status and Taxation
You count as a full-year resident if you were domiciled in Idaho for the whole year, or if you kept a home in Idaho for the entire year and spent more than 270 days in the state.5Idaho State Tax Commission. Idaho Residency Status and Taxation Domicile is your true, permanent home, and it stays in place until you both intend to leave it and set up a new permanent home elsewhere.6Cornell Law Institute. Idaho Admin Code r. 35.01.01.030 – Resident
Residents have to file an Idaho return whenever they are required to file a federal return. Part-year residents and nonresidents must file once gross income from Idaho sources (or, for part-year residents, combined income while living in Idaho plus Idaho-source income after leaving) tops $2,500.7Idaho State Legislature. Idaho Code 63-3030 – Persons Required to Make Returns of Income Below those thresholds, filing may still make sense to recover withheld tax or claim the grocery credit.
Deadline, Extensions, and Late Costs
Idaho returns are due April 15, matching the federal deadline.8Idaho State Tax Commission. Need an Extension to File Your Idaho Income Tax Return You get an automatic six-month extension to October 15 if your prepayments cover at least 80% of this year’s tax or 100% of last year’s.9Idaho State Tax Commission. Extensions If the required payment comes to $50 or less, you do not have to make it. An extension gives you more time to file, not more time to pay.
Filing late without a valid extension costs 5% of the unpaid tax for each month or partial month the return is late. Paying late after a timely-filed return costs 0.5% per month.10Idaho State Legislature. Idaho Code 63-3046 – Penalties and Additions to Tax The minimum penalty is $10, and the combined penalty caps at 25% of tax due. Unpaid tax also accrues interest, set at 6% for 2026.11Idaho State Tax Commission. Interest Rates If you cannot pay in full, file anyway. The late-filing penalty runs ten times faster than the late-payment penalty.