Severance tends to pop up on the public radar either in instances of executive compensation or when a tax or related change in the law takes place. Such cases tend to be guided by precedent and existing policy. When it comes to severance as part of company policy for all employees, however, no standard appears to exist.

That's what RiseSmart found when it surveyed more than 250 U.S. human resources managers about their employee transition policies. While the most often cited reason for offering severance to departing workers was "to take care of employees," rarely did they all get taken care of with a severance check.

"When asked why they provide severance, the majority of the HR professionals selected as their top three reasons to 'take care of employees,' 'limit company liability,' and 'protect employer brand,'" said Sanjay Sathe, president and CEO of Rise Smart.