Idaho charges a 6% sales tax on vehicle purchases, and a matching 6% use tax when you bring a vehicle into the state from elsewhere. The Idaho vehicle sales tax applies whether you buy from a dealer or a private party, and it’s paid to your county assessor’s motor vehicle office when you title the vehicle. What varies is the taxable amount, which exemptions you can claim, and what paperwork you bring with you.
The 6% Rate and How It Applies
Under Idaho Code § 63-3619, the state taxes the retail sale of motor vehicles at 6%. If you buy outside Idaho and bring the vehicle in, Idaho Code § 63-3621 imposes a complementary 6% use tax based on the vehicle’s value, with the recent purchase price treated as presumptive evidence of that value.1Idaho State Legislature. Idaho Code Section 63-3621 – Imposition and Rate of the Use Tax – Exemptions
If you already paid sales tax to another state on the same vehicle, Idaho credits that amount against what you owe here. Pay 4% somewhere else and you owe Idaho the 2% difference.2Legal Information Institute. Idaho Admin Code r 35.01.02.106 – Vehicle Sales, Rentals, and Leases Keep the original bill of sale or dealer receipt showing the tax you paid; the county needs it to apply the credit.
What Idaho Actually Taxes
Trade-Ins Reduce the Taxable Price
When you trade a vehicle to a dealer as partial payment, Idaho subtracts the trade-in value before calculating tax. Idaho Code § 63-3613 excludes “any sums allowed on merchandise accepted in payment of other merchandise” from the sales price.3Idaho State Legislature. Idaho Code 63-3613 Buy a $30,000 truck, trade in a car valued at $10,000, and you pay 6% on $20,000. That’s $1,200 instead of $1,800.
Manufacturer Rebates Don’t
Manufacturer rebates do not reduce the taxable price. Because the rebate comes from a third party rather than the retailer, Idaho treats it as cash applied after the sale. Even if the dealer hands you the rebate up front and gets reimbursed by the manufacturer, the full pre-rebate price is taxable.4Legal Information Institute. Idaho Admin Code r 35.01.02.051 – Discounts, Coupons, Rebates, and Gift Certificates A $2,000 rebate on a $35,000 vehicle still leaves you owing 6% on $35,000.
Private Sales Need a Bill of Sale
In a private sale, you need a bill of sale or receipt showing the actual price paid. A canceled check by itself won’t be accepted. If you can’t provide a bill of sale, the county calculates tax using the “average trade-in price” from the most recent NADA Official Used Car Guide for that make, model, year, mileage, and condition. The same NADA-based valuation applies to barter or exchange transactions where there’s no documented cash price.2Legal Information Institute. Idaho Admin Code r 35.01.02.106 – Vehicle Sales, Rentals, and Leases A vague handshake deal can easily cost more in tax than the actual purchase price would have.
Exemptions Worth Knowing
Idaho Code § 63-3622K treats certain vehicle transactions as nontaxable occasional sales. Each exemption comes with fine print.
Sales Between Family Members
Sales between family members within the second degree of consanguinity — parents, children, siblings, grandparents, and grandchildren — are exempt, but only if the seller originally paid sales or use tax on the vehicle. If the vehicle came to the seller through a prior exempt transaction and was never taxed, the family sale becomes taxable.5Idaho State Legislature. Idaho Code Section 63-3622K – Sales Tax A parent who received a car tax-free through a business transfer can’t turn around and sell it tax-free to their child.
Both buyer and seller must complete Form ST-133, confirming the family relationship and the earlier tax payment. The family exemption applies only to motor vehicles. ATVs, UTVs, snowmobiles, off-road motorcycles, and trailers don’t qualify.6Idaho State Tax Commission. Form ST-133 Sales Tax Exemption Certificate Family or American Indian Sales
Transfers Between You and Your Business
Transferring a vehicle between yourself and a business you own can be tax-exempt, but the structure matters. A transfer between an individual and their sole proprietorship isn’t taxed, because it’s the same legal entity. For corporations, partnerships, LLCs, and S-corporations, the transfer has to be solely in exchange for equity, and the person putting the vehicle in must have previously paid sales or use tax on it at a rate of at least 6%.5Idaho State Legislature. Idaho Code Section 63-3622K – Sales Tax These capital asset transfers use Form ST-133CATS rather than the standard ST-133.7Idaho State Tax Commission. Sales and Use Tax Guide for Vehicle Transactions
Enrolled Tribal Members
An enrolled member of an Indian tribe who buys a vehicle and takes delivery within reservation boundaries doesn’t owe Idaho sales tax. The retailer verifies tribal enrollment (typically with a tribal ID card) and must deliver the vehicle on the reservation. Both parties sign Form ST-133 to certify the on-reservation delivery.8Legal Information Institute. Idaho Admin Code r 35.01.02.091 – Sales to Indians
Moving to Idaho or Buying Out of State
New Residents
If you move to Idaho with a vehicle you already own, you generally don’t owe use tax on it, provided you bought it while living in another state and used it primarily outside Idaho. A registration or title from your previous state issued more than three months before your move serves as proof. If you bought the vehicle less than three months before moving, Idaho presumes you acquired it for use here and charges the 6%.9Legal Information Institute. Idaho Admin Code r 35.01.02.107 – Vehicles and Vessels New residents arriving from states with no general sales tax must complete Form ST-102 when they apply for an Idaho title.
Active-Duty Military
Active-duty military members and their spouses don’t owe use tax on vehicles they personally owned before receiving orders to Idaho, or before three months prior to the move, whichever is shorter. An out-of-state registration or title predating the orders is accepted as proof. There’s no special break on vehicles purchased while stationed here. And if your home of record is Idaho, the state treats you as an Idaho resident for tax purposes wherever you’re stationed.9Legal Information Institute. Idaho Admin Code r 35.01.02.107 – Vehicles and Vessels
Nonresidents
If you’re not an Idaho resident and your vehicle is registered in your home state, you don’t owe Idaho use tax as long as the vehicle isn’t used in Idaho more than 90 cumulative days in any consecutive 12-month period. A day of use means presence in the state for more than 16 hours in a 24-hour period. Every buyer named on the purchase, registration, and title must be a nonresident, and any business entity involved can’t be formed under Idaho law. Nonresident full-time students at an accredited Idaho postsecondary institution are also exempt.1Idaho State Legislature. Idaho Code Section 63-3621 – Imposition and Rate of the Use Tax – Exemptions
Forms You’ll Need
Wrong or missing paperwork is the usual reason for a second trip to the county office.
- Bill of Sale (Form ITD 3738) is your primary proof of price in a private sale, capturing the vehicle description, selling price, odometer reading, and seller’s certification. Without it, the county taxes you on NADA guide value.
- Form ST-133 is for family sale exemptions and American Indian exemptions. Both buyer and seller sign.6Idaho State Tax Commission. Form ST-133 Sales Tax Exemption Certificate Family or American Indian Sales
- Form ST-133CATS handles capital asset transfers to or from corporations, partnerships, LLCs, and similar entities.7Idaho State Tax Commission. Sales and Use Tax Guide for Vehicle Transactions
- Form ST-102 is for new residents arriving from states without a general sales and use tax who are claiming the use tax exemption.9Legal Information Institute. Idaho Admin Code r 35.01.02.107 – Vehicles and Vessels
Form ST-101, the general Sales Tax Resale or Exemption Certificate, is not used for vehicles. The Tax Commission’s own instructions direct vehicle buyers to Form ST-133 instead.10Idaho State Tax Commission. Form ST-101 Sales Tax Resale or Exemption Certificate
When and Where to File
You title the vehicle and pay sales tax at your county assessor’s motor vehicle office. The clock depends on how you got the vehicle:
- Bought in Idaho from a dealer: the dealer files within 30 days of delivery. If the dealer doesn’t, you have 30 days from the transfer to file yourself.
- Bought in Idaho from a private party: 30 days from the purchase date.
- Bought outside Idaho: 30 days from when you enter the state.
Miss the window and there’s a flat $20 late-filing penalty per transaction, no matter how late.11Idaho Transportation Department. Vehicle Titles
Title Fees
Every title carries a $14 statutory fee split between the state highway account and the county expense fund. Most counties add an administrative fee, and totals range from $14 in counties with no admin fee (Bannock and Caribou, for example) up to $32.75 in Blaine County. Idaho’s larger counties commonly land between $20 and $24.12Idaho Transportation Department. County Registration and Title Fees Title fees are separate from the 6% sales tax and from registration costs, which vary by vehicle age, type, weight, and county.
County offices generally accept cash, checks, and credit cards, though card payments sometimes carry a small processing fee. Once the clerk processes your application and confirms the tax has been paid, the title is generated and mailed to you.