Are you talking about changing the actual plan (i.e., it's no longer Blue Cross; it's now United Health Care); changing the plan but not the carrier (it's no longer Blue Cross Blue Shield Premier, it's now Network Blue); changing details within the same plan (the deductible is now $1500 instead of $1000 per year); or no changes to the plan but changes to the premium that the employee has to pay?
Just FYI, if I had a dollar for every time I saturated the employees with information about changes to the plan and still had someone come back later and tell me that I never told them (to the point where I could often pull out of the employee's file a form that they signed acknowledging the changes) I could retire.