What defines a mutual insurance company that has the right to assess policyholders additional premiums?

A mutual insurance company that has the right to assess policyholders additional premiums is defined as a mutual assessment insurer. This type of company operates on a mutual basis, meaning it is owned by the policyholders rather than stockholders. In a mutual assessment insurer, policyholders may be assessed additional premiums if the loss experience of the company exceeds expectations. This structure allows the insurer to maintain financial stability and ensure that all policyholders share in the risk and the costs associated with unexpected claims.

In contrast, other types of companies mentioned in the options do not necessarily have this assessment feature. For example, a stockholder company is owned by shareholders and operates for profit, whereas a participating insurer is one that offers policies eligible for dividends but may not assess additional premiums. The notion of a beneficiary company is unrelated to how insurance companies are structured financially. Thus, the mutual assessment insurer is distinct in its ability to collect additional funds based on policyholder assessment as needed.