The date on which a person’s age, for insurance purposes, changes. In most Life Insurance contracts this is the date midway between the insured’s natural birth dates. Health insurers frequently use the age of the previous birth date for rate determinations. On the date of age change, a person’s age may change to that of the last birth date, the nearer birth date, or the next birth date, depending upon the way in which the rating structure has been established by that particular insurer.