This is the 'biggest mistake' you can make when quitting your job, according to career experts

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When was the last time you daydreamed about quitting your job? 

It might be tempting after a heated email exchange or stressful week to call your boss, air all of your grievances, and turn in your two weeks' notice. For many Americans, it's not just wishful thinking — over the past six months, millions of workers have quit their jobs, including more than four million in September alone. 

But people who leave their jobs often make one mistake that can hurt their careers: burning bridges with their previous employer. 

Anthony Klotz, an organizational psychologist and professor at Texas A&M who first coined this quitting spree as "The Great Resignation," tells CNBC Make It that once you decide to resign, the power balance at work shifts. "You don't need your managers because you've made a plan to move on without them and the question becomes, what are you going to do with that power?" he points out. 

The worst mistake people who quit their job make is abusing that newfound power and giving in to the temptation to quit "in some grand fashion," Klotz adds. "Often, if we haven't been treated well by the organization or have a toxic manager, we think, 'I'm going to use this power to write an email or do something to get even for this unfair treatment,'" he continues. "But only in rare situations does anything good come out of that."

If you have serious concerns about your manager before leaving a job, Klotz recommends scheduling a meeting with an assistant manager or a different higher-up on your team and calling attention to the issue there instead. 

LinkedIn career expert Andrew McCaskill echoes Klotz's observation, noting that the worst move people can make when quitting is "not being gracious in their exit." "They don't give their employer enough notice, they check out of work long before they finish their projects or they talk poorly about their managers in person or online," he explains.

It's also dangerous to badmouth your previous employer to a hiring manager, or anyone at your next job, McCaskill adds, because that could signal to a new employer that "you might be a disgruntled worker and would speak poorly about other organizations if you don't agree with something they do or a decision they make." 

Don't assume that two weeks is enough time to give your boss notice of your departure, either. "We often think two weeks notice is the standard, but that differs widely by industry, so you should do some research to figure out the standard notice period before officially quitting," Klotz advises. Indeed and Glassdoor offer detailed guides for how to calculate your notice period. 

McCaskill shares a simple tip to avoid these gaffes: be just as kind and judicious about how you handle your employer in your exit as you were when you were interviewing for the job. "Remember how excited you were to join the organization and how you were very careful about how you managed and presented yourself in the beginning," he says. "Do that same mental gymnastics when you're on your way out and you'll make good decisions." 

Check out:

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