U.S. employees are giving away billions and billions of dollarsaway to their employers in unspent vacation, a new report finds.

The study by Project: Time Off claims that U.S.companies have $272 billion of unclaimed vacation on their balance sheets.That is linked to an estimated 658 million vacation days thatemployees didn’t use in 2015.

For the study authors, the figures should be a wake-up call notjust to employees, who are giving away extra work, but toemployers, who are overseeing millions of workers who clearly don’tfeel comfortable claiming the benefits that they have beenoffered.

Suffice it to say, while some workers may love their jobs toomuch too much to take vacation, many simply feel pressured not totake a day off. And that’s not a good sign in terms of employeemorale.

Unused vacation days are a sign that workers aren’t striking awork-life balance and are at risk of burnout.

"Beyond the red mark on balance sheets, not taking time offhurts employee engagement and productivity, affects talentretention, and expedites burnout — all of which hurt a company'sbottom line,” says report author Kate Dennis in a statementaccompanying the study’s release.

The higher up in an organization somebody is, the more likelythey are to not claim all of their vacation. While just over halfof employees (53 percent) did not use all of their paid time off,59 percent of managers and 67 percent of executives forgo vacationtime that they have earned.

That executives and managers are forgoing more vacation islikely linked to the fact that they generally are given morevacation. Somebody with five weeks of PTO is probably more likelyto leave some vacation on the table than a worker with only twoweeks of vacation a year.

However, the survey shows a unique nexus of factors that preventsenior managers from taking time off.

Whereas only 26 percent of executives and 33 percent ofemployees say that they avoid vacation because they fear returningto a “mountain” of unaddressed work, 55 percent of top-levelmanagers said that was a big reason they don’t take all of theirvacation.

Similarly, 52 percent of senior managers say they worry thatnobody can do their work while they’re away on vacation, comparedto only 27 percent of employees and 34 percent of executives.

Far more senior managers said that they find it harder to takevacation as they move up in the organization, compared to 23percent of workers and 38 percent of executives.