: You generally pay sales tax in the state where you register the vehicle, not where you buy it .
: Missouri and Illinois have reciprocity agreements. Usually, you should not be charged Illinois sales tax at the dealership .
: Tell the Illinois dealer upfront that you are a Missouri resident registering the car in Missouri .
: If the dealer incorrectly collects Illinois tax, you will receive credit for that amount toward your Missouri tax bill, but you will still have to pay any difference if Missouri's rate is higher .
You must title and register the car in Missouri within of purchase to avoid penalties . You will need the following at your local Missouri License Office : Faq - Motor Vehicle - Titling Registration
If you live in Missouri and buy a car in Illinois, you will primarily handle taxes and registration in your home state of Missouri . Sales Tax and Reciprocity
: You will owe the Missouri state sales tax of 4.225% plus any local taxes based on your Missouri residence . Registration Requirements in Missouri
