When Is a Smog Check Necessary?

A smog check is generally necessary in the following instances:
Registration Renewal: Most vehicles over eight model years old need to have a smog check every two years as part of the registration renewal process through the DMV.
Change of Ownership: A smog check is required for selling or transferring a vehicle, except if the vehicle is four model years old or newer.
Out-of-State Vehicles: Out-of-state vehicles are required to have a smog check before they can be registered in California, regardless of age.