Do you know about your employees' side jobs?

A fair amount of workers have side jobs, but many don’t let their employers know about it, according to Clutch’s report, “How the Gig Economy Affects the Workplace in 2018.”

The online marketing platform provider surveyed 521 workers and found that more than one-third of employees (36 percent) have at least one part-time gig, and nearly one in five (17 percent) are currently seeking a side job. More than two-thirds of employees with side jobs (69 percent) say their primary goal is to earn more money, while others say it’s about developing new skills (9 percent) or pursuing a passion (8 percent).

Related: The new retirement: Gigging?

A quarter of workers with side jobs (25 percent) say their employer doesn’t know that they participate in the gig economy. However, this includes 19 percent of workers with side jobs who don’t think their employer would mind. Among workers whose employers are aware of their participation in the gig economy, some work in industries where side jobs are common (37 percent), while others’ employers don’t require details about outside work commitments (35 percent).

“There are really only two situations where a manager should interfere with an employee’s side job: if the work or the client poses a conflict of interest or if it’s interfering with the employee’s primary job,” management consultant Alison Green tells Clutch. “But if it’s not a conflict of interest and it’s not getting in the way of the person’s work, the manager should stay out of it.”

For employers, companies are most likely to hire contract or freelance workers for short-term projects that require technical or specialized knowledge, according to the report.

Nearly one-third of companies (29 percent) hire temporary workers who offer technical skills, including experience with analytics, IT, and data science, as well as web, mobile, or software development. Companies also hire temporary workers for marketing and creative projects (14 percent), administrative tasks (12 percent), customer service (10 percent), and accounting (10 percent).

“Hiring gig economy workers allows scaling companies to take on technical projects on a case-by-case basis,” the authors write. Companies are also relying on remote workers to complete specific business functions, as nearly one in five (18 percent) outsourced some tasks to remote workers in the past year.

“Outsourcing can take the form of hiring independent contractors or working with a business process outsourcing company that provides third-party services such as HR, payroll, customer service, or other functions,” the authors write. “In addition to hiring gig economy workers, companies reduce operating costs by outsourcing tasks to remote workers.”

Businesses that hire gig economy workers must realize that they typically balance multiple work commitments, according to the report. “Companies can benefit from temporary workers’ specialized skills, and leaders are essential in guiding successful collaboration,” the authors write.