According to Beth Weissenberger, CEO of The Handel Group, an executive coaching firm based in New York, "Workplace gossip is unproductive. It breeds resentment and becomes a roadblock to effective communication and collaboration." Thus, you can compare an employee who gossips frequently to one who misses deadlines or hands in incomplete work, as both workers compromise efficiency. When conducting a performance evaluation for an employee who frequently gossips, you must reflect this negative habit in his score and communicate with him openly about it.
Give your employee the appropriate scores on her performance evaluation for things like quality of work, quantity of work, initiative and adaptability.
Give your employee scores for fundamentals like cooperation, employee relations, communication and leadership skills that reflect how minor or serious his tendency to gossip is. Consider highlighting those numbers and writing "come see me" next to them.
Talk to your employee about her work. Praise or give constructive criticism as necessary.
Tell your employee that his scores for things like cooperation, employee relations, communication skills and leadership skills are lower than they would ordinarily be because of his tendency to gossip. Explain that you think gossip hurts productivity, morale and communication in the workplace. Explain why.
Tell your employee that, as suggested by the website Employee Performance Solutions, "While it's only natural to be interested in what's going on in other people's lives, I'd like you to resist the temptation to share personal information that you may be privy to or have learned from others."
Tell your employee that if she is frustrated with a company policy or procedure, or finds that something unfair or unjust has occurred, she is to express her concerns to you directly.