The 18-Month Rule Isn't in the Regs — Here's What Actually Matters

A carrier calls you Friday afternoon with capacity on a lane you're scrambling to cover. They're 14 months old. Your TMS flags the authority age, and you decline — because that's the rule, right? Eighteen months minimum, everyone knows it.

Except FMCSA never wrote that rule. You made it up. Or more precisely, your industry made it up, passed it around, and now enforces it like it's federal law.

That's not entirely wrong. There's real data behind it. But treating it as a binary cutoff — 17 months is a no, 19 months is fine — is how brokers leave good carriers on the table while approving dangerous ones. And after Montgomery v. Caribe Transport II, "I checked the authority age" is not a legal defense. It's barely even a starting point.

Where the 18-Month Rule Actually Came From

The origin isn't a specific CFR section. It comes from FMCSA's new entrant program, codified in 49 CFR Part 385, Subpart D. That subpart requires carriers who've been operating for fewer than 18 months to complete a new entrant safety audit, typically within their first 12 months of operation. It also gives FMCSA authority to conduct safety reviews during this window and to place new entrant carriers out of service if the audit reveals critical violations.

The program exists because FMCSA's own research showed new entrant carriers have a meaningfully higher involvement rate in crashes during their first 18 months. The agency uses this window to catch carriers who shouldn't be on the road before they rack up a body count.

So the industry logic went: if FMCSA watches these carriers extra closely for 18 months, maybe I should too. Fair enough. But somewhere along the way, "watch them more carefully" got compressed into "automatically decline them," and now brokers are applying a one-bit risk filter to a multi-dimensional problem.

When 18 Months Is the Right Call

Sometimes the binary does work. If a carrier is 8 months old, has 3 total inspections, and you can't verify fleet size independently — pass. The data isn't there yet. You have almost nothing to evaluate, and FMCSA would agree with you. The inspection history is too thin to tell you anything meaningful about their OOS rate, their vehicle maintenance culture, or their driver qualification practices. You're essentially betting on a carrier you can't vet.

Same answer if the carrier is 10 months old and those 3 inspections already show a 33% OOS rate. You don't need more data. You've seen enough.

Under 49 CFR § 385.319, FMCSA can revoke a new entrant's registration if they fail the safety audit or fail to submit to one. That risk alone — that a carrier in your load history could have their authority pulled mid-transit — is a legitimate reason to be conservative with young authority. A carrier that loses operating authority while your load is on their trailer is a bad day that ends in claims, customer calls, and potentially a litigation file.

So yes. For thin-data, young-authority carriers, 18 months is a reasonable default.

When the Rule Fails You — In Both Directions

Here's where I see brokers make mistakes.

The false pass. A carrier clears the 18-month mark and gets treated like they've graduated. But 18 months of existence doesn't mean 18 months of good data. Take a carrier like MC-9218476 / DOT-4153021 — 26 months old, which gets them past most brokers' automated filters. But pull the SAFER snapshot and you see 9 total inspections, 3 OOS events, and a Crash Indicator BASIC at the 82nd percentile. The authority's been around long enough to look safe in a one-field check, but the underlying data says something different.

I've seen carriers at 3 years old with a more dangerous record than some 14-month-old carriers I've approved. The magic number gives people false confidence.

The false decline. This is the one that costs brokers money and good carrier relationships. MC-1247893 / DOT-3567102 — 11 months old. Before you close the file: 47 roadside inspections, zero OOS events, no crashes on record, clean Clearinghouse result, verifiable fleet of 12 units confirmed against MCS-150 filing. This carrier has more usable data at 11 months than plenty of 2-year-old carriers you've happily approved.

The inspections are what matter. Inspections create the dataset FMCSA BASICs run on. A carrier who's accumulated 47 inspections in under a year — probably because they're running high-volume lanes with frequent weigh station exposure — has given you enough signal to make a real risk assessment. The 18-month clock was a proxy for data accumulation. If the data's there, the proxy becomes redundant.

What the Signal Actually Is

What you're really trying to answer isn't "how old is this carrier?" It's two questions: Do I have enough data to evaluate this carrier? And does that data tell me they're safe?

The data-sufficiency question is mostly about inspections. FMCSA needs a minimum number of inspections to generate a reliable BASIC percentile — generally 5 in the relevant category over 24 months. Under that threshold, the percentile is suppressed and you're flying blind on that metric. That's the real risk with young carriers: not that they're new, but that you can't see their record clearly yet.

Once a carrier clears meaningful inspection thresholds, evaluate them the same way you'd evaluate any carrier: OOS rate against their peer group, specific BASIC categories that fit your freight (Unsafe Driving and Crash Indicator for most loads; Vehicle Maintenance if you've had issues; HOS Compliance if you're time-sensitive), and crash history read for severity, not just count.

Authority age becomes a tie-breaker when everything else is ambiguous — not a first-pass filter that makes the rest of the analysis unnecessary.

What This Means Post-Montgomery

Montgomery v. Caribe Transport II removed the legal insulation brokers had in the 7th and 11th Circuits. You can now be sued in state court for negligent carrier selection. Which means a plaintiff's lawyer is going to look at your carrier file and ask whether your vetting process was reasonable.

"They were over 18 months old" is not a reasonable vetting process. It's a timestamp. A jury doesn't know what 18 months means, and opposing counsel will explain that you checked one field, confirmed the number was big enough, and tendered the load.

But the flip side is also true: "They were 14 months old, but I documented 47 clean inspections, a 0% OOS rate, no crashes, a clean Clearinghouse hit, and COI with adequate limits" is a defensible record. You made a judgment call supported by evidence. That's what due diligence looks like.

The standard isn't a threshold. It's a process.

The Carrier You Should Actually Worry About

I said earlier that carriers over 18 months get a false pass. Let me be specific about when that happens.

A carrier who ran under one MC, surrendered authority after an OOS order or a compliance review, and then re-registered under a new MC is older than their current authority says. Same principals, same equipment, same safety culture — but the new MC starts the clock over. If you screen MC-6741038 and see 9 months of history, that's fine. If you don't notice that the same officers at the same address had MC-4829501 revoked 14 months ago for a pattern of critical violations, you've vetting-washed a problem carrier.

The 18-month rule doesn't catch this. It can't. This is where you need to look at principals, not just authority dates — cross-referencing the officers listed on SAFER against revocation history.

How I Document This

When I approve a carrier under 18 months of authority, the file has to show the reasoning. Here's what I capture:

• Authority grant date and total months active at time of approval
• Total inspection count across all BASICs (Driver Fitness, Vehicle Maintenance, HOS, Unsafe Driving, Crash Indicator, Controlled Substances/Alcohol, Hazmat if applicable)
• OOS rate in applicable categories, compared to national average (from SAFER snapshot)
• Any suppressed BASICs and why (threshold not met — which I note explicitly)
• Crash history: how many, severity if details available
• Clearinghouse result date
• COI with coverage limits and effective dates, verified against FMCSA L&I database
• MCS-150 fleet count and whether it's consistent with inspection VINs
• Any compensating controls: COI certificate holder added, continuous monitoring enabled, verified dispatcher contact

The last line is the one that matters most. If I'm approving a carrier I have less data on than I'd like, I want to know the second anything changes — coverage lapses, OOS orders, authority status updates. That's what the monitoring is for.

The 18-month rule isn't wrong. It's just incomplete. The data behind it is real, but the binary cutoff is a shortcut that cuts both ways. Know why the rule exists, and you'll know when to apply it and when to look harder.

— Mason Lavallet

Founder, DOTScreener.com