Operators of U.S. commercial vehicles such as heavy trucks, tow trucks and passenger buses, must have a commercial driver’s license (CDL) issued by their state. California's licensing requirements, like those of other states, comply with federal standards established by the Commercial Motor Vehicle Safety Act of 1986. California's Department of Motor Vehicles licenses all California drivers. New California residents transfer their CDL licenses by following the same procedures as first-time CDL applicants.

Residency Requirement

Federal law mandates that a commercial vehicle operator can have only one license at a time. When a commercial driver relocates to California, he must obtain a state-issued CDL within 10 days of moving to the state. He must also surrender his current CDL.

Age Requirement

An applicant must be at least 18 years old to obtain a CDL to operate a commercial vehicle within California borders. She must be at least 21 years old to obtain a CDL to drive a commercial vehicle across state lines. She must also be 21 years old to drive a passenger bus or to transport hazardous materials within California or across state lines.

CDL Application

An applicant must submit a completed and signed CDL application to a local DMV office, and pay the appropriate fees. He must also have his thumbprint and photograph taken, and present proof of his Social Security number in the form of a Social Security card, a Medicare card, a U.S. Armed Forces identification card or a military separation document. The applicant must provide a valid birth certificate, a U.S. passport, or another formal identification document to substantiate his date of birth.

Background Check

Because his current CDL license was issued from another state, an applicant must undergo a background check of his driving record. He must submit details to the California DMV about every driver’s license that has been issued to him from another state within the last 10 years.

Medical Examination

An applicant must submit a medical examination form that certifies he meets the medical standards required to drive a commercial vehicle. A physician, chiropractor, physician assistant, nurse practitioner or advanced practice nurse who is licensed in the United States must have performed the examination and completed the medical form within the last two years.

Required Tests

A CDL applicant must pass a vision test, which is given at the DMV office. He must also pass a written examination about California traffic laws and signs, and performance tests that demonstrate his knowledge and skills to operate a commercial motor vehicle.

Requirement for Hazardous Materials Endorsement

Any commercial driver seeking a hazardous materials endorsement with his CDL must undergo a security threat assessment by the U.S. Transportation Security Administration. This federal agency checks criminal history records, legal status, and international databases to make sure the driver is not a security risk to the country.