You usually need a SMOG check if
- Your DMV registration renewal notice says a SMOG certification is required.
- You are selling a vehicle and need to provide a valid SMOG certification to the buyer.
- You are registering a qualifying vehicle in California for the first time after it was purchased or previously registered out of state.
- Your DMV notice specifically says the test must be done at a STAR station.
You may be exempt if
- Your gasoline, hybrid, or alternative-fuel vehicle is eight model years old or newer and you are only dealing with biennial renewal.
- Your gasoline, hybrid, or alternative-fuel vehicle is four model years old or newer and the question is change of ownership.
- Your vehicle is electric or a motorcycle.
- Your vehicle falls into one of the older gasoline or diesel exemption categories recognized by California.