You’ve heard of quiet quitting, where workers stay put at a job but don’t give it their all.

Now there’s stealth working, whereby employees, lying to their bosses about where they actually are, disguise the fact that they are laboring from far reaches of the country, if not the globe, Fortune reports.

They get around revealing where they are by dressing the part of the office headquarters (think sweaters or suit) and by using the company’s virtual private network (VPN) to log in at all hours, even if it’s 2 a.m.

Ninety-five percent of knowledge workers crave flexible schedules, a Future Forums survey found. Some have even become nomads, living in vans that they drive from one inexpensive locale to another.

As remote work became the norm for knowledge workers during the COVID pandemic, some countries, like Portugal, even began issuing digital nomad visas.

The problem is, these workers are not working to full capacity, costing employers in untold lost productivity.

If the employee is operating from a state or a country where the company is not registered, it can rack up tens, if not hundreds of thousands of dollars, in taxes and fees for the employer. There are also serious legal liabilities, insurance and cybersecurity to consider.

“The COVID free pass is running out,” says Chantel Rowe, vice president of product management at Topia, an HR technology platform. “We’ve got big problems to deal with, without having tax and immigration authorities cracking down on us.”

And employers thought getting people to reject working from home and to return to the office was difficult enough.