Is an ATV title required in Idaho?

Yes. In order to receive a 'restricted vehicle' plate, your vehicle must be titled in your name. If you have not previously titled your vehicle, you will be required to do so unless you have a motorbike or ATV you purchased before January 1, 2009, or you have a UTV purchased before July 1, 2006. You will need to bring ownership documents with you to register. Include any signed title from the seller, manufacturer's certificate of origin, prior registration, and bills of sale you may have. Applicable sales tax will also be due.

Source: Idaho DMV Restricted Vehicle Registration FAQ'S