HR experts reveal what they really do with your exit interview info—and how honest you should be

In the early part of my career, exit interviews seemed like a formality — just one of many parts of the process of leaving a job. I was especially hesitant to give feedback. What was the point of explaining what could be improved upon at a job I was already leaving?

But in the past few years, I starting taking my exit interviews seriously. At the same time, however, I wondered whether my feedback would actually make a difference.

Was it possible that I had been too honest? If so, what were the consequences? What did HR do with the information they collected? Would they share my name with managers and colleagues I worked with?

So I reached out to two HR experts (both have nearly 50 years of combined experience) and asked them about what most people don't — but should — know about exit interviews, and how employees on their way out should handle them:

"Though as an employee you may feel disposable, that's far from the truth," Carolina King, chief people office at Lucas Group, tells CNBC Make It.

King, who previously managed HR teams for large companies including AT&T and Turner Broadcasting, says it's incredibly costly to bring on new individuals into any business — small or large. "Retention is one of the main focuses of human resource departments," she says.

When someone decides to move on from a position, the exit interview is the company's chance to find out what went wrong, so they can learn from them and avoid losing other employees for similar reasons in the future.

King says a lot of exiting employees go into the interview and rattle off a list of complaints about the company. She stresses the importance of having concrete examples of where things went wrong, rather than general grievances.

HR professionals are looking for feedback in exit interviews to be as specific as possible, using factual statements to describe your time at the company.

For example, rather than simply saying you didn't get along with your manager, King suggests taking it a step further and letting HR know exactly when and what went wrong. What was the point at which your relationship with a manager eroded? Was there a policy you found inappropriate or exclusionary? Was a particular event that made you want to leave?

As with all feedback, it's important to proceed with caution, and be balanced and fair, Traci Wilk, senior vice president of people at The Learning Experience, tells CNBC Make It.

If you don't think you can find constructive words and phrases to describe your time with the company, she suggests telling the interviewer you'd like to postpone the interview. This should provide enough time and distance to craft and refine your narrative.

"This is likely not to be the final connection with your employer and your company's leadership, so it's an opportune time to ensure you're leaving on a good note and not burning any bridges," explains Wilk, who previously worked as an HR executive at Starbucks for seven years.

"Even if you're leaving an unpleasant work situation, speaking too harshly could have a long-term impact," she adds.

No matter how short or lengthy your interview was, HR reviews each and every piece of information you shared.

According to King, HR teams at many organizations take the data and redact any identifying information like names or dates. Then, they do an analysis on a quarterly or annual basis looking for trends.

For example, HR will notice if a certain manager has a particularly high turnover rate, or if a company policy negatively impacted a number of people. King says she has launched several investigations, changed corporate policies and coached managers based on exit interview feedback.

Similarly, as a result of exit interviews, Wilk says her company recently redesigned their new hire immersion process, which involves specific activities that ensure role clarity, a foundation of trust and communication from the start.

"Over the years, I've found that the primary reasons an employee quits is less about compensation and perks, and more about unclear expectations and a lack of trust with their manager," she says.

A lot of people try to avoid conflict or uncomfortable conversations at all costs. Sometimes this means holding onto information about something inappropriate or possibly even illegal happening in your workplace.

King says the exit interview isn't the ideal time to surface these situations for the first time. Rather, tell someone at the organization if anything happens that is against the law, discriminatory or that constitutes harassment so they can deal with it sooner rather than later.

"Don't wait. Do it right away. It's such a common mistake for exiting employees to assume that HR or management is aware if something illegal happened," King says. "I can't tell you the number of times that it's a shocking bit of information I learned through an exit interview that I would've 100% addressed immediately."

According to King, you should approach an exit interview — especially if you had a negative experience at the company — from the perspective of: "I'm leaving, I found another opportunity, but here's what could be changed for the betterment of others."

Hearing this made me feel good about how I handled one of my more recent exit interviews: I compiled a list of all the topics I wanted to discuss with both my manager and HR, then ran it by some colleagues to ask if there was anything else they wanted me to bring up, given that I could do so without repercussions.

Like many people, I've made some of my closest friends and valued colleagues through my jobs. So when you leave a position, it's nice to do whatever you can to improve the work environment for them.

Elizabeth Yuko is a bioethicist and writer, as well as an adjunct professor of ethics at Fordham University. She has written for publications including The New York Times, The Washington Post, CNN, The Atlantic, Rolling Stone and Salon.

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