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. A carrier that hasn't refiled within the 24-month deadline is out of compliance with a basic obligation, and every self-reported field on its record (fleet size, mileage, contact info) is at least that stale. fleetfax flags an overdue filing.
A precision note you'll see reflected in how fleetfax words things: the public record carries the date the form was filed, not per-field timestamps. 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.
Related terms
USDOT number
The federal registration number every interstate carrier must hold. The primary key of the federal carrier record.
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.