Each impairment in this guide has a "probable underwriting action," with some impairments having a table rating listed. Standard mortality is defined as 100%. Each table rating represents a 25% increase in mortality costs.
Table ratings are usually used for impairments that increase in severity with increasing age. Flat extra premiums are usually used for accident hazards which are the same at any age, such as occupation or driving, and can be either temporary or permanent. A few medical impairments, such as cancer, can be assessed a flat extra premium because the extra death claims are the same at all ages. A combination table rating and flat extra rating is assessed when a risk presents an immediate extra hazard temporarily and increases in severity with age. For example, a history of heart attack frequently requires a temporary flat extra premium because of the extra mortality following the event and a table rating for the underlying disease which progresses with age.