Paid days off from work aren't a guarantee for many Americans, but even when they do get them, they're leaving them on the table.

A majority, 78%, of U.S. workers say they don't take all their PTO days, and it's highest among Gen Z workers and millennials, according to a new Harris Poll survey of 1,170 American workers.

Younger professionals say they don't ask for time off because they feel pressure to meet deadlines and be productive, and they get nervous requesting PTO because they don't want to look like a slacker, says Libby Rodney, chief strategy officer at The Harris Poll.

That's not to say they're not taking breaks — they're just not telling their boss.

Millennials are most likely to be 'quiet vacationing'

Millennials in particular have found workarounds to play hooky. Nearly 4 in 10 say they've taken time off without communicating it to their manager.

Similar shares say they "move their mouse" to show they're still active on their company's messaging platforms (like Slack or Microsoft Teams) when they're not really working, and they've scheduled a message to send outside of regular hours to give the impression they're working overtime.

"There's a giant workaround culture at play," Rodney says. While Gen Zers tend to be more vocal about workplaces that shame people for wanting to ask off work, millennials would rather take matters into their own hands but under the radar.

"They will figure out how to get appropriate work-life balance, but it's happening behind the scenes," Rodney adds. "It's not exactly quiet quitting, but more like quiet vacationing."

The pitfalls of unlimited PTO

When people feel the need to sneak out for breaks, it's a sign that their workplace doesn't have a supportive PTO system or culture in place, Rodney says.

Bosses can alleviate that tension in a number of ways, she adds: They can be more transparent about what requesting time off looks like, normalize taking PTO by taking time as a boss, support when their employees take off, and mandate a certain amount of time off.

Unlimited PTO isn't necessarily the solution. Workers who receive 11 to 15 days of PTO each year are more likely to use up their days, Rodney says, but there's a significant drop-off once people get 16 or more days.

Instead, employers can get creative in their PTO benefits, like offering company-wide week-long shutdowns around major holidays, paying new hires to take a vacation before they start, or requiring employees take a certain number of PTO days each quarter to pace their time off throughout the year.

More broadly, many Americans from the Harris Poll survey say the U.S. should adopt laws common in Europe that enforce boundaries on working hours vs. personal time, like extended vacation policies (think: a month off in August), longer lunch breaks, workweeks shorter than 40 hours, and regulations that protect slower response time outside of work hours.

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