There's no single answer to this question. Smog check requirements (or equivalent emissions testing) vary significantly by state and sometimes even by county or municipality within a state. The age of the vehicle at which it's no longer required for testing also differs. Some states may exempt older vehicles entirely, while others might have different requirements based on the vehicle's type and emission standards.
To find the answer you need, you should check your state's Department of Motor Vehicles (DMV) website. They will have the most up-to-date and accurate information on smog check requirements where you live.
