An employer-paid medical exam is a taxable benefit unless negative exam results will negatively affect employment status

CRA considers that employer-paid medical examinations give rise to a taxable benefit unless they are required as a condition of employment.  It will infer that there is no such requirement if "the employee can exercise discretion as to whether to take an annual examination by the employer's physician," or (even more astonishingly) "unless a medical exam with negative results impacts employment status in some manner."

Neal Armstrong.  Summary of 19 February 2014 T.I. 2013-0508501E5 under s. 6(1)(a).