Workers in 2018 quit their jobs at the highest rate since 2001—and probably will next year, too

Experts say that the only real way workers can significantly increase their earnings in the current labor market is to quit their jobs.  

In 2018, millions of workers listened to this advice. From July through September, 2.4 percent of the U.S. workforce voluntarily quit their jobs, the fastest rate since 2001. According to the most recent Job Openings and Labor Turnover Survey (JOLTS) from the Bureau of Labor Statistics (BLS), over 3.5 million Americans quit their jobs every month.

Here's why so many people quit this jobs in 2018, and why the same will be true for 2019:

Quitting was the surest way for workers to get a raise in 2018. Slow wage growth and a tight labor market meant that workers had a better chance of increasing their earnings by leaving their current job for a new one, despite an otherwise healthy labor market.

"For any type of employment search, you won't find a better time than right now," Thomas Moran, CEO of staffing agency Addison Group tells CNBC Make It.

Brian Kropp, vice president at research firm Gartner, largely echoes Moran's outlook, pointing to strong job growth and low unemployment. "For most employees, you couldn't have imagined a better year than 2018 on most, but not all, dimensions," Kropp tells CNBC Make It. "On the surface, it seems like it was a great year for employees. However, what we still didn't see in 2018 was any real significant increase in wage rates."

Wages are currently growing just 1 percent faster than inflation but the average increase in compensation for a worker who quits their old job for a new one is about 15 percent. "You're never going to get that 15 percent [increase] by staying at your current job," says Kropp. "That's just not going to happen."

"For many, [quitting] is a smart move, as there's a clear advantage to increasing your earning potential by switching jobs," Andrew Chamberlain, chief economist at Glassdoor, tells CNBC Make It.

A second reason that workers left their jobs in 2018 is because they weren't moving up.

"People didn't get promoted in 2018," says Kropp. "We saw a reluctance from companies to actually significantly promote people. Today, the average employee is at the same level for about four and a half years. Pre-global financial crisis, that was about two and a half years, so the average employee is at the same level roughly 50 percent longer than they were a decade-plus ago. And that's a sign that it wasn't a great year for employees."

As Kropp points out, the number of years that workers spend waiting for a promotion has increased dramatically since the Great Recession.

"One of the big things that happened during the global financial crisis is that organizations pulled out all sorts of layers of middle management, which actually makes it harder to get promoted," says Kropp. "Simply put, there are fewer opportunities to get promoted."

Experts like Kropp aren't optimistic that wage growth and opportunity for advancement will change drastically in 2019.

"We've yet to see that big breakthrough [in wages] occur, and maybe we never will," says Kropp. "Maybe the economy shifted. Because if we're not seeing growth now, there might have been a systematic shift in the labor market that indicates that it's not going to happen."

Gartner surveyed compensation executives and found that most employers are only anticipating an average 2 percent to 2.5 percent increase in overall compensation budgets for 2019. Furthermore, few companies who removed middle management positions during the financial crisis have replaced these positions, making it harder for workers today to get a promotion.

One thing that experts are confident about however, is that the tight labor market will continue into 2019, especially for specific tech-focused skills. This will give workers lots of opportunities to earn raises by moving to a new organization.

"The in-demand and challenging labor market will continue for sure," Larry Nash, U.S. Director of Recruiting at EY tells CNBC Make It.

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