An endorsement that must be attached to the auto liability policy of certain regulated motor carriers to ensure that federally mandated coverage (e.g., required liability limits and environmental restitution coverage) is in place. The endorsement does not actually provide insurance except on a reimbursement basis. For example, a standard unendorsed Insurance Services Office, Inc. (ISO), commercial auto policy contains a pollution exclusion that would preclude coverage for environmental restitution. In the event the broadened pollution liability coverage endorsement (CA 99 48) is attached to a regulated motor carrier's policy, the pollution exclusion is modified but not totally deleted. In either event, if the MCS-90 endorsement is attached, the insurer's obligation with respect to such a situation is determined by the MCS-90 endorsement provisions regardless. If the policy would provide such coverage even without that endorsement, the insurer pays the claim and the endorsement effectively has no impact on the issue. However, if the claim would not have been covered under the policy except for the MCS-90 endorsement provisions, the insurer pays the claim and then has the right to seek reimbursement from the insured.

Requires certain vehicles to carry minimum limits of insurance coverage to satisfy public liability and environmental restoration claims that may arise from accidents. The minimum required limits range from $750,000 to $1 million to $5 million per accident, depending on the type of commodity transported (i.e., nonhazardous or hazardous and, in the case of hazardous substances, the specific category of such).

A commercial auto policy introduced by Insurance Services Office, Inc. (ISO), in 1993 to address the needs of the motor carrier (i.e., trucking) industry. Coverages available include auto liability, trailer interchange, and auto physical damage; other coverages are available by endorsement. The policy was developed as an alternative to the truckers policy because of the changes taking place in the industry. That is, the truckers policy is applicable only for "for-hire" motor carriers, whereas the motor carrier policy is appropriate for all types of motor carriers—for-hire, private, or a combination of both types of operations.