Glossary
MCS-150 (biennial update)
The MCS-150 is the Motor Carrier Identification Report: the registration form behind a carrier's USDOT record. It carries the company's self-reported profile, including legal name, addresses, contact details, fleet size (power units), and annual mileage. Federal rule (49 CFR 390.19) requires every carrier to refile it at least every 24 months, whether or not anything changed.
Why the filing date matters
The MCS-150 date is the freshness stamp on everything the form contains. Every self-reported field on the record (fleet size, mileage, contact info) is at least as old as the last filing, and every fleetfax report shows when that was. FMCSA paused enforcement of the filing deadline in 2026 during its registration system transition, so fleetfax does not currently flag an overdue filing.
The public record carries the date the form was filed, not a date for each field. A fresh MCS-150 date means the carrier refiled the form on that date; it does not certify which individual fields changed or were verified. fleetfax attributes dates to filings, never to individual fields, because that's all the record actually supports.
Self-reported vs observed
Fleet size on the MCS-150 is what the carrier says about itself. The inspection record is what the road says. When the two disagree in interesting ways (a claimed fleet with no inspection trail anywhere, for instance), that mismatch is itself a signal, and fleetfax surfaces it. See the live fleet age tracker →
Related terms
USDOT number
The federal registration number every interstate carrier must hold. Every other federal record on the carrier is filed under it.
Operating authority
FMCSA's grant of legal permission to operate for hire: common, contract, or broker. Active, inactive, pending, revoked, and the gaps in between.
Power units
The self-propelled vehicles a carrier reports operating: trucks and truck tractors, not trailers. The fleet-size figure on the federal record, self-reported on the MCS-150.
fleetfax reads public FMCSA data and is not affiliated with FMCSA or the U.S. Department of Transportation. This page explains terminology; it is not legal advice.