USDOT Number Marking Requirements

Last updated: October 20, 2026 · Sources: 49 CFR 390.21T, FMCSA Motus pages

Quick answer: Each self-propelled CMV must show your legal name or single trade name (as on your MCS-150) and "USDOT" followed by your number, on both sides, in letters that sharply contrast with the background and are readable from 50 feet in daylight while the vehicle is stopped (49 CFR 390.21T). Painted lettering or a removable device both work.

What the marking must show (390.21T)

• Your legal name or a single trade name of the business, as listed on your MCS-150 registration.
• "USDOT" followed by your USDOT number, for example USDOT 1234567.

How it must look

• On both sides of the self-propelled CMV.
• In a color that sharply contrasts with the background.
• Readable from 50 feet in daylight while the vehicle is stationary.
• It can be painted on or a removable device.

Leased trucks and other names on the door

If another company's name appears on the truck, your name must be preceded by "operated by" (390.21T(b)(3)).

Motus and USDOT suffixes

FMCSA's registration system, Motus, launched for all registrants in May 2026. Existing USDOT numbers don't change. New registrants see USDOT "suffixes" in Motus; they are not a vehicle-marking requirement.

Checklist

• ☐ Name on the truck matches your MCS-150 exactly
• ☐ "USDOT" plus the number, on both sides
• ☐ Contrasting color, readable from 50 feet
• ☐ "Operated by" added if another company's name is on the truck
• ☐ Re-check after any name change (and update your MCS-150 in Motus)

Keep the whole setup in one place

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FAQ

Do I need my MC number on the truck? The marking rule in 390.21T requires your legal or trade name and "USDOT" with your USDOT number.

Can I use magnetic signs? Yes. The marking can be painted or a removable device, as long as it meets the size, contrast and placement rules.

Do I put the Motus suffix on the truck? No. FMCSA says USDOT suffixes shown in Motus are not a vehicle-marking requirement.

How big do the letters have to be? The rule sets no fixed size. They must be readable from 50 feet in daylight while the vehicle is stationary.

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Educational only, not legal advice. Carrier Launch Kit is not affiliated with FMCSA or USDOT. Check the current rule in the eCFR.

Educational only, not legal advice. Affiliate disclosure.