Where the numbers on this site come from

The data

The MCS‑150 pages, meaning the single lookup and the list check, use one source: the FMCSA Company Census File, published by the U.S. Department of Transportation at data.transportation.gov/resource/az4n-8mr2. It's free. It needs no API key and no account. Those lookups query it live from your browser, so there is no cached copy of ours sitting between you and the record.

The carrier history page is different, and it's worth being precise about because it changes what a coverage claim means. It reads three further datasets plus the census: out-of-service orders from FMCSA's New Entrant Safety Assurance Program, authority revocations, and insurance filing history. Two of those three stopped being updated when FMCSA moved registration to the Motus system in May 2026, so they are archives with a stated end date, not live feeds. The Covers column on that page is measured each time we sweep, because every one of these tables reports a fresh last-updated timestamp daily whether or not its contents changed. Details are on that page.

About nine in ten orders in the out-of-service file carry a New Entrant Revoked reason. That is a safety audit a carrier failed or never answered inside its first 18 months, and it's not a roadside action, so the history page names the programme, and does not call everything an out-of-service order.

Checking when the census was last updated…

The filing rule, and which version of it's in force

49 CFR 390.19T requires a motor carrier to update its MCS‑150 every 24 months, and it sets each carrier's timing from the USDOT number. The last digit gives the month. The next-to-last digit gives the year: odd digit, odd-numbered years, even digit, even-numbered years. Paragraph (b)(2) says the form must be filed by last day of the assigned month, so a carrier isn't late during their own month.

The section number matters and the obvious guess is wrong. 49 CFR 390.19 and the whole Unified Registration System subpart, 390.201 through 390.209, are suspended indefinitely. eCFR labels that subpart E-suspended, and 88 FR 80184 of 17 November 2023 reads: Amend Sec. 390.19 by: a. Lifting the suspension of the section; … d. Suspending the section indefinitely. The T section is the one that applies. FMCSA's own FAQ still cites the suspended one, so we don't follow it there.

390.19T(b)(4) states the consequence: a person who fails to complete the biennial update is subject to the penalties prescribed in 49 U.S.C. 521(b)(2)(B) or 49 U.S.C. 14901(a), as appropriate, and deactivation of its USDOT Number.

Filing early counts, and the window is 12 months

FMCSA publishes this and it decides every threshold on the site: FMCSA considers any update of an MCS‑150 or MCS‑150C that was completed by a motor carrier, Intermodal Equipment Provider (IEP), or carrier that has been issued a Hazardous Materials Safety Permit (HMSP) at any time during the 12 months immediately preceding the biennial update due date to satisfy the biennial update requirement.

Two things follow. A carrier who files on the first day of that window and then waits out the whole cycle can sit at 35 months with nothing wrong, which is where the 36-month figure people quote actually comes from. And a 25-month-old form can be perfectly fine, so a flat 24-month cutoff invents delinquency. We don't use one.

We call a record past due only when the form on file is older than 24 months and older than the 12-month window before that carrier's most recent expired deadline. Both tests. Missing the window on its own can fire at 13 months, because a deadline that expired last month had its window open 13 months ago, and a carrier in that position has still filed inside the 24 months the rule names. Those get a separate label that says the call is arguable.

Who the rule doesn't reach, which is most of the apparent problem

390.19T(a) reaches motor carriers and intermodal equipment providers. It doesn't reach brokers, freight forwarders, shippers or cargo tank facilities. The section that would have covered them, 390.201(b)(1), is one of the suspended ones.

Those businesses hold USDOT numbers and sit in the same file with an empty or twenty-year-old MCS‑150 date, because they never had to file the form. So we read the census entity-type field before saying anything, and a registrant the rule doesn't reach is never flagged.

What "active" means here

It means the census registration status field says the registration is active. The MCMIS data dictionary defines it as the status of the record, and it explicitly includes intrastate-only carriers issued a number by a state. It's a field in a file. It's not a finding about safety, insurance, or operating authority, and a census date isn't a compliance determination. FMCSA makes compliance determinations. We read a record and do arithmetic on a date.

The date field itself needs the same care. The MCMIS Company Census Data Dictionary defines MCS150_DATE as the date typed or written on the MCS‑150 form used to update the record. Any change filing resets it, and the form carries one combined reason code covering both a biennial update and a change, so which kind it was can't be recovered. A second FMCSA dictionary calls the same field the latest date the form was filed. Those are different things, and FMCSA publishes both, so we describe it as the date on the most recent form on file and nothing more.

The 36% number, corrected

One exemption we can't resolve

390.19T(i) exempts a motor carrier that registers its vehicles in a state taking part in the PRISM programme, provided it files the required information with that state. The census doesn't record whether a carrier is in that position, and FMCSA publishes state participation only as an image. So a carrier can look stale here and owe nothing. Every past-due result on this site says so on the result itself.

What we don't publish

Compliance vendors quote a figure of about 12% of registrants missing their biennial update each cycle. We traced it to a filing service's blog post carrying no attribution, and found no FMCSA, OIG, GAO or Federal Register document that quantifies it. So it's not on this site. The only primary measurements we located are DOT Inspector General reports from 2004 and 2006, both of which predate the deactivation mechanism that would change the rate.

FMCSA's own carrier counts are also not comparable to anything here. Its published figure counts carriers with recent activity in the past three years, which is a different denominator from a registration status field.

Update cadence

Lookups read the census live, so a result carries whatever the file held at the moment you asked. The population counts come from a full sweep of the file and carry the date of that sweep.

The code

The schedule arithmetic is one module with 78 tests behind it, and the same module runs the lookup on this page, the list check, and the sweep that produced the counts above. One of those tests asserts that no result statement anywhere claims a carrier is out of compliance. Another forbids citing the suspended sections.