If you currently have a hazardous materials endorsement, federal rules require you to take the hazardous materials written test every time you renew the endorsement.
You must present a Federal Security Threat Assessment letter from the Transportation Security Administration (TSA) and proof of U.S. Citizenship or Lawful Permanent Residence to renew a CDL with a hazardous materials endorsement.
A vision test must be passed. No other CDL written tests are required unless you want to upgrade the group designator, remove an air brake restriction, or add a new endorsement when renewing your license.