In Illinois do you have to pay sales tax when purchasing a used car from a private seller?

Yes. You must pay sales tax whenever you purchase a vehicle, no matter who you bought it from. If you buy from a dealer, the dealer will collect the sales tax then. If you get the car from a private individual, though, you'll need to pay sales tax when you first register the vehicle. Even if the car was a gift.

You will need to file an RUT-50 form. This free form is not available online, but you can pick one up at any Secretary of State office.

You may also order it by mail from the Winchester Warehouse, a clearinghouse for the state's forms, free of charge. Send your request, including the form number and your full mailing address, to:

• Winchester Warehouse

• Attention: Forms Distribution

• 3701 Winchester Road

• Springfield, IL 62707

Or you can simply call (217) 782-7132 and and ask to have the form sent to you. Have the form number and name handy when you call.

Once you have the form, you can call the Illinois Department of Revenue at (800) 732-8866 to find out how much sales tax is due.

Source:

http://www.dmv.org/il-illinois/registration-faqs.php