There's really only one reason to do an exit interview - to potentially learn from an individual who is leaving your company whatever it is they felt they couldn't say while they were working there. (Ideally if communication was effective prior to their leaving, you would know just about everything else.) And the only reason you would want to know this information is to be able to garner a perspective that could be immensely valuable in improving your company.
So while the questions are important - so is the space that is created before you ask the questions. Let them know why you are asking the questions and what you will do with their answers. They need to know that the time they spend with you is important to you (not just an HR check list to do) and that the information they reveal to you will be used to improve the company and the conditions for the co-workers they leave behind. Let them know that in no way will their honest responses impact how you would choose to refer them in the future. (Ideally any reference letters have already been provided.) The person conducting the interview should be someone the person leaving trusts and will open up to - this may or may not be their immediate supervisor.
Now that you're clear on why you want to conduct an exit interview and have created a healthy safe space for the conversation, here are the top 9 questions to ask:
- What did you absolutely love about working here?
- When did you feel most appreciated and valued at our company?
- What fond memories do you have of working here? (company culture stories that you don't want to lose)
- Who here at this company is going to be the most impacted by you leaving? (look at both the emotional and workload aspects of this question)
- What were some of your biggest frustrations about working here?
- If you were the owner of our company, how would you do things differently?
- What should we truly know that you never felt like you could tell us while you were working here?
- When you leave here, and talk to your friends and family about our company, what will you say? How will you describe your experience here, no holds barred?
- What else do you think we should know that we didn't ask?
Of course thank them for their candor and thank them for their contribution to the company (specifics are ideal.) Also make sure to give them another way to reach you once they leave should they think of anything else you should know.