(1)    The prohibition against employment discrimination on the basis of age applies only to discrimination against an individual who is age 40 or over.

   (2)   Notwithstanding sub. (1) and s. 111.322, it is not employment discrimination because of age to do any of the following:

      (a)    To terminate the employment of any employee physically or otherwise unable to perform his or her duties.

      (b)    To implement the provisions of any retirement plan or system of any employer if the retirement plan or system is not a subterfuge to evade the purposes of this subchapter. No plan or system may excuse the failure to hire, or require or permit the involuntary retirement of, any individual under sub. (1) because of that individual’s age.

      (d)    To apply varying insurance coverage according to an employee’s age.

      (e)    To exercise an age distinction with respect to hiring an individual to a position in which the knowledge and experience to be gained is required for future advancement to a managerial or executive position.

      (f)    To exercise an age distinction with respect to employment in which the employee is exposed to physical danger or hazard, including, without limitation because of enumeration, certain employment in law enforcement or fire fighting.

      (g)    To exercise an age distinction under s. 343.12 (2) (a) and (3).