Whether what you have written about is legal or illegal depends upon what is presently stated in the presumed employer employee handbook that you have. Most likely the handbook will spell out what is allowed as to health care benefits for an employee where you work. As such, I suggest that you carefully read the document. If there is nothing addressing the issue that you have written about in the handbook, you need to consult with a labor attorney about your matter in that at first blush it does not seem proper for you to be debited so much per hour for seeking insurance if other employees do not receive the same treatment at work.