When an employee leaves for another job, the typical cost to replace him or her is more than $10,000, says William M. Mercer Inc. And 20% of the companies Mercer surveyed indicated the replacement cost is more than $30,000. The highest areas of turnover: technology workers and administrative staff. The compensation. solution: better pay. Why? Of those surveyed, 59% said the major reason employees left was due to dissatisfaction over compensation.