Each state has slightly different requirements for renewing a vehicle's license plate. Generally, the vehicle owner needs authorized documents with a social security number, current address, the driver's license, license plate number and certification that the vehicle is non-polluting, if living in an area requiring this.
No matter the state, most drivers need to renew their license plates on an annual basis. This requirement helps the Department of Motor Vehicles keep track of cars on the road. The renewal fees also help pay for the upkeep of the roads and staffing the DMV.
Every state runs its DMV in a slightly different manner. However, most try to make registration renewal a simple process for the owner. Once a vehicle has been registered with the DMV, the owner usually only needs to bring the old registration card back in for renewal, along with a current driver's license and smog certification, if needed.
That card should have all of the information on it that the DMV needs to look up the vehicle information. The driver's license has the owner's information, and the smog certification shows that the vehicle meets state environmental regulations and requirements. If the vehicle owner has moved since last renewing the plates, a document with a current address is also required.
The DMV may require that the owner show documentation with the social security number on it. If this is not displayed on the driver's license, the car owner may provide a social security card or another legal document with the number on it.