The culprits are primarily girls who take off their clothes and offer sexual services in front of a web camera. Skatteverket estimates there are between 300 and 500 individuals who earn money this way. So far the agency has identified close to 200 people.

What the majority have in common is that they have neglected to declare their income.

“Young people are usually seen as poorly informed about how to file their taxes. That might be one explanation, but another reason is that their clients don’t want to be identified,” Dag Hardyson, project manager for Skatteverket’s investigation of online businesses, told TT.

In the last three years, Skatteverket has looked into three different areas: pills, poker and porn. During the course of their investigation, they noted that paid pornography sites have had an increasing difficulty peddling their wares as so much free content is available. But they also discovered that the demand for “webcam girls” has increased.

At first, Hardyson and his team didn’t believe the phenomenon was particularly widespread in Sweden.

“But our colleagues in Holland said, ‘We have a problem, so it’s obvious that you have a problem’,” he said.

They also explained that the success of the “webcam girls” rests in the fact they can speak Swedish with their Swedish customers, and it is that interaction that is most important.

The business is entirely legal, but requires those offering the service to register for a corporate taxation certificate, as well as maintain records of expenses and income. According to Sveriges Radio, only one of the individuals audited by Skatteverket has submitted an income declaration.

The businesses are estimated to generate around 40 million Swedish kronor ($5 million), at least 20 million of which is tax revenue.