§383.93 lists the endorsements that may be added to a CDL: (T) double/triple trailers; (P) passenger; (S) school bus; (N) tank vehicle; (H) hazardous materials; and (X) the combined tank + hazardous materials endorsement. Each endorsement has its own knowledge-test requirement under §383.117–.123 and, for H/X, a TSA security threat assessment under 49 CFR Part 1572.
Severity weight
Severity weight 3 in the Driver Fitness BASIC. The carrier-side §383.37(a) prohibition on letting an under-endorsed driver operate makes this a two-citation event when found at roadside.
What triggers an endorsement
- Towing a second or third trailer (combination longer than one trailer): T endorsement.
- 16+ passenger capacity including the driver: P endorsement.
- Operating a school bus that meets §383.5: S endorsement (in addition to P).
- Operating a tank with a rated water capacity of 1,000+ gallons mounted on a CMV: N endorsement (note: §383.5 definition matters — empty tank operation still requires the endorsement).
- Placarded hazardous-materials quantities: H endorsement plus TSA STA.
How to prevent it
- Maintain a per-driver endorsement table and cross-reference at dispatch.
- TSA STA for H/X must renew every five years — track the renewal as its own date.
- New-entrant carriers entering hazmat or passenger work: re-check every driver before the new operation begins.
How Roadworthy HQ helps
Roadworthy HQ tracks each endorsement (and the TSA STA expiration for H/X) as a discrete item, with the relevant CDL copy retained in §391.51 and a dispatch-time check against the vehicle and commodity assignment.