Montana Auto Loan & Sales Tax Calculator

When you buy a vehicle, the state where you register it charges sales tax on the purchase price — typically collected by the dealer at the time of sale and remitted to the state, rather than paid separately by the buyer later. This is different from a general retail sales tax in that it's tied to vehicle registration, so even a private-party purchase or an out-of-state purchase usually triggers tax when you register the vehicle in your home state. The single biggest variable between states is trade-in treatment. Many states allow you to subtract your trade-in vehicle's value from the purchase price before calculating tax — meaning a $30,000 purchase with a $10,000 trade-in is taxed on $20,000, not the full $30,000. Other states tax the full purchase price regardless of any trade-in, which can add hundreds or thousands of dollars to your total cost compared to a trade-in-friendly state. A smaller number of states cap the maximum tax on a vehicle purchase regardless of price, and a handful of states charge no vehicle sales tax at all. Local county and city taxes can also stack on top of the state rate, so the total you pay at the dealership may exceed the base state rate shown here — always confirm the exact combined rate for your specific location before finalizing a purchase.