§390.21T is the marking rule in force. §390.21 itself is suspended indefinitely; its eCFR effective-date note records the latest re-suspension at 84 FR 40294, August 14, 2019. §390.21T requires every self-propelled CMV subject to the FMCSRs to display, on both sides of the vehicle (§390.21T(c)(1)):
- The legal name or a single trade name of the motor carrier operating it, as listed on its MCS-150 (§390.21T(b)(1))
- The carrier's USDOT number, preceded by the letters "USDOT" (§390.21T(b)(2))
- In letters that contrast sharply with the background, readily legible during daylight from 50 feet while the CMV is stationary, and kept that way (§390.21T(c)(2)–(4))
If any other person's name appears on the vehicle, the operating carrier's marking must be preceded by the words "operated by" (§390.21T(b)(3)). The marking can be painted on or a removable device, as long as it meets the same legibility rules (§390.21T(d)).
Operational implications
§390.21T does not appear in FMCSA's SMS Appendix A (version 3.21, revised May 2026), either among the roadside violations or on its list of acute and critical violations found in investigations, so it carries no CSA severity weight. Neither does the suspended §390.21.
Common findings
- USDOT number on the vehicle doesn't match the carrier of record (frequently leased operators)
- DBA name displayed without the legal name from the MCS-150
- Markings that can't be read from 50 feet in daylight: too small, too little contrast, or peeled and faded
- A leased unit still showing the owner's name with no "operated by" line for the carrier running it
How to prevent it
- Update vehicle markings whenever the legal name on the MCS-150 changes
- Leased operators: verify the carrier of record markings match the actual carrier authority being operated under
- Photograph each vehicle's markings at acquisition for the audit binder
How Roadworthy HQ helps
Roadworthy HQ does not track vehicle markings; there is no markings date or photo on the vehicle record. Roadside inspections are logged on the vehicle (date, state, level, driver, number of violations, out-of-service or not), and an out-of-service inspection starts the 15-day §396.9(d)(3) repair-certification countdown.