Last checked Nov 10, 2026
Buying a car in Idaho
The tax you will pay, whether your trade-in lowers it, what the dealer may charge for paperwork, and where to title and register. Taken from official Idaho sources.
- State tax on vehicles
- 6%
- Trade-in lowers tax
- Yes
- Doc fee limit
- No cap
- Deadline to title or register
- 30 days
details below
Sales tax on a car in Idaho
Idaho charges a state sales tax of 6% on vehicle purchases.
If there is no bill of sale for a private purchase, tax is collected on the average trade-in value in the NADA Official Used Car Guide. Idaho gives credit for general sales tax properly paid to another state.
Does a trade-in lower the tax?
A trade-in accepted by a dealer as part of the same transaction reduces the taxable price. Trade-in allowances are not allowed on private-party sales.
Example, state tax only. On a $30,000 car with a $10,000 trade-in, the taxable amount is $20,000, so the state tax is about $1,200. Without the trade-in it would be $1,800. Local taxes and fees are extra.
Dealer doc fees in Idaho
Idaho's dealer rules do not set a maximum; they require any documentation fee to be listed separately from other fees and identified as a dealer document preparation fee that is subject to sales tax.
The documentation fee is taxed along with the vehicle.
Whatever the rule, the fee is part of your out-the-door price. Ask for it in the written quote and negotiate the total, not the line. See dealer fees explained.
Title and registration
Titles and registrations are handled by the Idaho Transportation Department, Division of Motor Vehicles. An Idaho dealer prepares and files the title application within 30 days of delivery. For a private sale or an out-of-state dealer that does not file, the buyer must file with a county motor vehicle office within 30 days to avoid a $20 late-filing penalty.
Also worth knowing
- A VIN inspection is required when a vehicle comes from another state or has never been titled in Idaho.
- The Attorney General's advertising guidelines let a dealer leave the documentation fee out of an advertised price only if the ad discloses the amount of the fee.
Sources
- Idaho State Tax Commission: Sales and Use Tax Guide for Vehicle Transactions (EPB00060, 06-11-2025) (tax.idaho.gov)
- IDAPA 39.02.03: Rules Governing Vehicle Dealer's Principal Place of Business and Claims to the Idaho Consumer Asset Recovery Fund (adminrules.idaho.gov)
- Idaho Transportation Department: Vehicle Titles (itd.idaho.gov)
- Idaho Attorney General: Guidelines for Motor Vehicle Advertising and Sales (ag.idaho.gov)
Last checked Nov 10, 2026; next review by Feb 10, 2027. This page explains how the rules generally work and is not tax or legal advice. Rules change, so confirm with the state. Report an error.
Concierge
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