A BOP's simple rates work only if the insureds are alike. So every insurer that writes BOPs has eligibility rules, and the rating structure contemplates a homogeneous group of small and midsize businesses.

ISO rules look at business size and how complex the loss exposures are. Size tests in the CDI outline: - Total floor area: less than 35,000 square feet - Number of stories - Annual gross revenue: not more than $6,000,000 per location A risk must pass every test. The revenue test looks at one location at a time: two stores with $4,000,000 each both pass, even though the total is $8,000,000.

Business type and operations also matter. Restaurants and contractors are no longer excluded, but they must meet class rules; for example, ISO limits an eligible contractor's annual payroll to $300,000 and its exterior work to 3 stories. Ineligible businesses in the outline: automobile-related businesses, bars, financial institutions and manufacturing occupancies.

ISO's 2025 program overview adds detail the outline lacks: offices are limited to 6 stories, offices get a larger floor area limit, and some auto service and light manufacturing classes are eligible. On the exam, use the outline's 35,000 square feet and its list of ineligible businesses.

Proprietary programs: an insurer may file its own BOP program, and its eligibility rules may differ from ISO's. A store over ISO's floor area limit can still fit another insurer's program.