Could you go into greater detail about what taxes does the company pays when an NSO is exercised in a year when a person is no longer employed? Is it just the e

Could you go into greater detail about what taxes does the company pays when an NSO is exercised in a year when a person is no longer employed? Is it just the employer's part of medicare and social security (7.5% up to 117000 as of 2014?) or is it something else?