Promotions are often given to people until they reach a level of incompetence.

What once was an incredible, capable employee, who was great as an individual contributor, will eventually be promoted into positions where they're incompetent—usually a managerial role. They'll then remain in these roles because they no longer exhibit competence for further promotion.

This is what Dr. Laurence J. Peter called The Peter Principle.

He concluded that people in a hierarchy rise through promotion to their level of incompetence. "Every position in a given hierarchy will eventually be filled by employees who are incompetent to fulfill the job duties of their respective positions."

You've likely experienced this before—being incapable or promoting somebody unfit for the job's duties.

For me, I've been the one to promote incompetence:

I managed my sales team for many years. I believed to get the company to the next level, I needed to promote someone to take over these duties, so I could continue to focus on higher-level activities.

An Account Manager had been working with me for years, and she developed incredible sales skills over that time. I knew the risks of pulling a top producer away from direct sales activities into a managerial role. Still, it was worth a try.

She failed miserably.

She hated it.

Management caused her so much mental pain and anxiety; I could feel it.

And it was all my fault.

Thankfully, I was aware of this and made a quick correction, but most leaders don't, and incompetence in managerial roles festers like a virus in an open wound.

Before you fail your team and your company by promoting people to incompetency, do these three things:

1/ Regularly assess people's skills.

Many valuable hard skills don't transfer directly into higher positions:

An example is someone who is an exceptionally skilled engineer but lacks the social skills to be an effective manager.

Or an incredible sales rep with strong leadership capabilities amongst her clients but lacks core day-to-day management traits.

Leaders must evaluate job skills and where someone falls on the capability spectrum before anyone is promoted to a new role.

Always ask yourself:

• What is this person's current capability in this area?

• How high are the stakes?

The answers will guide your decisions or next steps if they need more skill development.

You can start to evaluate people's skills by using low-risk trial periods.

2/ Establish trial periods.

The lowest risk decision you can make is creating a short-term experiment, where you test an employee's ability in a leadership role over a short period.

Here are a few ideas:

Experiment 1: Involve them in an upcoming quarterly or yearly planning session.

"We'd like you to be a guest participant at our next planning session."

Did they contribute and get involved?

Experiment 2: Have them mentor or support a particular team over 90 days. Make this their core objective for the quarter.

"I'd like your help mentoring the X team over the next 90 days. Are you up for the challenge? It will be a challenge."

Experiment 3: Have them take the leadership responsibility of a core team over 30, 60, or 90 days.

"Can we try an experiment? Would you be willing to lead this team for the next 30, 60, or 90 days and we'll see how it fits for you, for the team, and the company?"

No matter the experiment, the key here is to evaluate how they do every week. Don't just abdicate the experiment away.

Assign your team opportunities to learn and grow and "try" something.

If they're competent, promote them.

If not, let them stay where they are.

"Don't make it permanent as it's really hard to come back from that," coaches David Finkel.

And that's the biggest problem regarding The Peter Principle—a permanent change that leads to incompetent leadership.

3/ Assign regular training and mentors.

Chamath Palihapitiya has said the biggest problem in silicon valley is "we've gone through an entire decade of undertraining an entire generation of people."

He believes that "many of these people, unfortunately, don't have the skill set to execute at a high level." They needed more mentorship and a deeper understanding of institutional and industry knowledge. As a result, these people are "extremely underdeveloped and unable to run these businesses."

Current and future leaders need mentors to help them learn how to sharpen their saw, much like what an apprentice used to do.

Skills development isn't a set-and-forget-it mentality—everyone on the team must get ongoing mentoring and skills training.

It's up to the leaders to assign regular training before and after giving someone a promotion and ensure the training is tailored to the skills needed for the position.

In my company, everyone on my team must establish a quarterly skill development objective and key results (OKRs). After that, it's up to them and their managers to determine if they should focus on current skills they need to improve or core skills they need to develop to grow in the company.

Ongoing training and mentoring are crucial to the success of the company and the individuals in it.

It's a disastrous idea to let incompetence plague leadership roles—the cure is relatively easy to execute.