(1)    Beginning on July 1, 2011, in any employee retirement system of a 1st class city, except as otherwise provided in a collective bargaining agreement entered into under subch. IV of ch. 111 and except as provided in sub. (2), employees shall pay all employee required contributions for funding benefits under the retirement system. The employer may not pay on behalf of an employee any of the employee’s share of the required contributions.

   (2)   

      (a)    An employer shall pay, on behalf of a nonrepresented law enforcement or fire fighting managerial employee, who was initially employed by the employer before July 1, 2011, the same contributions required by sub. (1) that are paid by the employer for represented law enforcement or fire fighting personnel who were initially employed by the employer before July 1, 2011.

      (b)    An employer shall pay, on behalf of a represented law enforcement or fire fighting employee, who was initially employed by the employer before July 1, 2011, and who on or after July 1, 2011, became employed in a nonrepresented law enforcement or fire fighting managerial position with the employer, or a successor employer in the event of a combined department that is created on or after July 1, 2011, the same contributions required by sub. (1) that are paid by the employer for represented law enforcement or fire fighting personnel who were initially employed by the employer before July 1, 2011.