An applicant for a commercial driver's license is required to pass the commercial driver's license general knowledge test except: A Maryland commercial driver's license renewal applicant; A holder of a valid Maryland commercial driver's license who is applying for another class of commercial driver's license; and An applicant who is transferring a valid commercial driver's license, issued by another state, to a Maryland commercial driver's license. A Class A commercial driver's license applicant is required to pass the commercial driver's license combination vehicle knowledge test, except: A Maryland Class A commercial driver's license renewal applicant; and An applicant who is transferring a valid Class A commercial driver's license, issued by another state, to a Maryland commercial driver's license. An applicant for a double/triple endorsement is required to pass the commercial driver's license double/triple knowledge test, except: A Maryland Class A commercial driver's license renewal applicant with an existing double/triple endorsement; and An applicant who is transferring a valid Class A commercial driver's license with a double/triple endorsement, issued by another state, to a Maryland commercial driver's license. An applicant for a tanker endorsement is required to pass the commercial driver's license tanker knowledge test, except: A Maryland commercial driver's license renewal applicant with an existing tanker endorsement; and An applicant who is transferring a commercial driver's license with a tanker endorsement issued by another state to a Maryland commercial driver's license. Hazardous Materials Endorsement. An applicant for a hazardous materials endorsement is required to pass the hazardous materials knowledge test, except for existing commercial driver's license holders who are applying for a corrected or duplicate commercial driver's license. An applicant for the renewal or transfer of a commercial driver's license with a hazardous materials endorsement is required to pass the hazardous materials knowledge test regardless of the length of time the applicant has had a hazardous materials endorsement. An applicant for a passenger transport endorsement is required to pass the commercial driver's license passenger transport knowledge test, except: A Maryland commercial driver's license renewal applicant with an existing passenger transport endorsement; and An applicant who is transferring a valid commercial driver's license with a passenger transport endorsement, issued by another state, to a Maryland commercial driver's license. An applicant who wishes to drive a commercial motor vehicle equipped with air brakes is required to pass the commercial driver's license air brakes knowledge test, except: A Maryland commercial driver's license renewal applicant who has previously passed the test in this section; and An applicant who is transferring a valid commercial driver's license without an air brake restriction, issued by another state, to a Maryland commercial driver's license. School Vehicle Endorsement. An applicant for a commercial driver's license with a school vehicle endorsement is required to pass the school vehicle knowledge test. An applicant for the renewal, upgrade, or transfer of a commercial driver's license with a school vehicle endorsement is required to pass the school vehicle knowledge test regardless of the length of time the applicant has had a school vehicle endorsement, except: An applicant for the renewal or upgrade of a commercial driver's license with a school vehicle endorsement who has previously passed the school vehicle knowledge test; and An applicant renewing a commercial driver's license with a school vehicle endorsement issued before September 30, 2006, provided the applicant passes the school vehicle knowledge test before September 30, 2006. A school vehicle endorsement held by a commercial driver's licensee who has not passed the school vehicle knowledge test shall be cancelled without further action by the Administration at 12:01 a.m. on September 30, 2006. Cancellation of the school vehicle endorsement does not affect the validity of the commercial driver's license or any other endorsement. All applicants for a commercial driver's license with a school vehicle endorsement shall also meet the requirements for a passenger transport endorsement before the issuance of a school vehicle endorsement.