A more thorough explanation:

Assessable insurance is a type of insurance policy where the policyholder may be held responsible for losses of the insurance company beyond its reserves. This means that if the insurance company experiences a large loss, the policyholder may be required to pay additional funds to cover the cost.

For example, let's say a policyholder has an assessable insurance policy for their home. If a major disaster occurs, such as a hurricane, and the insurance company's reserves are not enough to cover all the claims, the policyholder may be required to pay additional funds to help cover the cost of the damages.

Assessable insurance policies are not very common and are typically only used in certain situations, such as with some types of property insurance policies.