Primary truck liability: what it covers, what the law requires, and where it breaks

Primary auto liability is the policy that answers when your truck hits someone. It pays damages the law says you owe for bodily injury and property damage caused by an accident that results from the ownership, maintenance or use of a covered auto, and it pays to defend you in a suit. Defense is on top of the limit under the standard ISO wording, and the insurer's duty to defend ends when the limit is used up by judgments or settlements.

For trucking, this policy does three jobs at once:

• It protects your balance sheet when a driver causes a wreck.
• It satisfies the law. Your insurer files proof of this coverage with FMCSA (the BMC-91 or BMC-91X) and, for Texas intrastate operations, with TxDMV (Form E). See FMCSA and TxDMV insurance filings.
• It is what brokers and shippers check first. A carrier packet that shows the wrong limit, the wrong named insured or a missing unit gets rejected. See carrier packet insurance rejected.

What it does not cover matters as much. The standard motor carrier form excludes damage to property you are transporting or that is in your care, custody or control (that is motor truck cargo), injury to your own employees (that is workers' compensation), damage to your own truck (that is physical damage), and most pollution from the load you are carrying (see truck pollution liability).

Most trucking liability is written on one of three ISO forms, or on a carrier's own form that borrows their structure. Knowing which one you have tells you which symbols to look for.

Motor Carrier Coverage Form (CA 00 20). This is the ISO form built for businesses that move property by auto, for hire or as a private carrier. It defines a motor carrier as a person or organization providing transportation by auto in the furtherance of a commercial enterprise. It uses symbols 61 through 71 and 79, and it includes trailer interchange coverage in its own section.

Truckers Coverage Form (CA 00 12). The older form, built around regulated for-hire trucking. ISO withdrew it in its 2010 multistate revision and replaced it with the Motor Carrier Coverage Form. You may still see its symbols (41 through 50) on older policies, quotes or certificates, or on carrier-specific forms that copy it.

Business Auto Coverage Form (CA 00 01). The general commercial auto form. Some underwriters write trucking accounts on it with the Motor Carrier Endorsement (CA 23 30), which adds cost-of-hire and gross receipts or mileage rating and a trailer interchange schedule. Owner-operators leased to a carrier usually see a business auto policy with the non-trucking endorsement (CA 23 09); see non-trucking liability.

Many trucking markets use their own manuscript forms. The names change; the questions do not. Which autos are covered, who is an insured, and when is the policy primary or excess?

The most common liability problem we see is not a low limit. It is a truck that is not covered at all.

On a symbol 67 policy, only the units listed on the schedule are covered autos for liability. Under the 10 13 edition of CA 00 20, a newly acquired unit is covered only if the policy already covers all autos you own or the new unit replaces one that was covered, and you tell the insurer within 30 days. Buy a third tractor, forget to call, and have a wreck on day 35, and the policy may not cover that tractor.

Here is where the MCS-90 comes in. The federal endorsement makes the insurer pay a final judgment for public liability "regardless of whether or not each motor vehicle is specifically described in the policy." So the injured person still gets paid. But the endorsement also says the insured agrees to reimburse the insurer for any payment it would not otherwise have made. Federal courts describe the MCS-90 as a suretyship that protects the public without changing the deal between you and your insurer. In plain terms, you would owe the insurer the settlement.

Symbol 61 (any auto) avoids most of this, but it costs more and many trucking underwriters will not offer it. If you are on a schedule, build a habit: no unit goes into service until the agent confirms it was added. See scheduled auto vs any auto.

When an owner-operator leases a truck to you, federal leasing rules require the lease to give you exclusive possession, control and use of the equipment for the term of the lease and to make you responsible for its operation (49 CFR 376.12(c)(1)). The lease must also state your legal obligation to maintain the insurance required by federal law, and it must say who provides other coverage, such as bobtail insurance, and what you will charge back for it (376.12(j)(1)).

Your liability policy has to match. On CA 00 20, leased tractors are covered autos when your symbols include them (typically 61 or 68, or by scheduling the leased units under 67). The form also sorts out which policy is primary:

• When you hire a unit from another motor carrier, your policy is primary if the lease does not require the lessor to hold you harmless, and then only while the unit is used exclusively in your business as a for-hire carrier. If the lessor holds you harmless, your policy is excess.
• When you lease your unit to another motor carrier, your policy is primary only if you agreed to hold that carrier harmless.
• A trailer follows the power unit it is attached to.

Read your leases with these rules in mind, and have an attorney review the hold-harmless language. For the owner-operator side of this picture, see leasing owner-operators insurance and who insures a leased owner-operator.

Your liability insurer, not you, files proof of coverage. Interstate for-hire carriers have a BMC-91 or BMC-91X filed with FMCSA, and the policy carries the MCS-90 endorsement. Texas intrastate carriers have a Form E filed with TxDMV. TxDMV says only the insurance company can file proof of insurance or a cancellation (Form K), but you are responsible for keeping your TxMCCS insurance record active.

Cancellation has its own clocks:

• Under 49 CFR 387.7, a policy with the MCS-90 can be cancelled by either side only on 35 days' written notice.
• Under 49 CFR 387.313, a filed certificate cannot be withdrawn until 30 days after written notice reaches FMCSA.
• Under Texas Transportation Code 643.104, an insurer may not terminate coverage for a TxDMV-registered carrier without giving TxDMV at least 30 days' notice.

Brokers see what is on your certificate and, through onboarding platforms such as RMIS, Highway, MyCarrierPackets and Carrier Assure, what FMCSA shows as your filing. Many brokers ask for $1,000,000 in auto liability even though the federal minimum is $750,000. See why brokers require $1 million and broker-carrier agreement insurance requirements.

Texas changed how commercial vehicle injury suits are tried. Chapter 72, subchapter B of the Civil Practice and Remedies Code, added in 2021, lets a defendant move for a bifurcated trial: the jury decides liability and compensatory damages first, and exemplary (punitive) damages in a second phase. If an employer stipulates that the driver was its employee acting in the scope of employment, ordinary negligence claims against the employer such as negligent entrustment generally stay out of the first phase, with exceptions for regulated carriers, including evidence about the driver's license, disqualification and out-of-service status.

That law changes how a trial runs. It does not cap damages, and it does not change what your limit is. A serious injury claim can still exceed $750,000 or $1,000,000. That is why most fleets carry an umbrella or excess layer over primary auto. For background on large verdicts, see what is a nuclear verdict. Have defense counsel, not your agent, advise on how chapter 72 applies to a particular claim.