Having a second job isn’t illegal, and many people take on extra work to boost their income. Traditionally, this meant working a full-time office job during the day and a part-time role in the evening. However, there’s a growing trend of individuals holding two full-time jobs without fulfilling their obligations to either employer—known as “polygamous working” or “moonlighting.”
With remote work becoming more common after Covid, it’s easier to juggle multiple jobs undetected. Influencers on social media often promote this as a way to increase income, especially during a cost-of-living crisis. But concealing simultaneous employment can amount to fraud.
How Fraud Is Identified
The National Fraud Initiative (NFI), part of the Public Sector Fraud Authority, detects cases of moonlighting using data from 1,100 public and private sector organisations. A recent pilot in London identified 23 cases, with overpaid salaries totalling £500,000. In an extreme case, someone held three jobs in government departments and withheld their employment history when applying for new roles.
The Risks of Polygamous Working
Balancing two full-time jobs can lead to poor performance, especially in safety-critical roles. Employers are also legally responsible for ensuring workers do not exceed 48 hours per week unless an opt-out agreement is signed. If an employee hides a second job, employers cannot track working hours properly, leading to:
- Legal penalties and unlimited fines
- Compensation claims if employee health is impacted
- Health and safety risks
Additionally, employers face concerns around confidentiality if a worker is employed by a competitor.
If deception is discovered, the employee risks repaying overpaid wages and potentially dismissal.
Signs of moonlighting. What employers should watch for:
- Declining performance—especially in previously strong employees
- Frequent absences or low engagement
- High stress and fatigue despite a reasonable workload
These issues may have other causes, but employers should consider polygamous working when addressing concerns.
Side Hustles: A Related Concern
Many workers, particularly younger ones, take on side hustles in their free time, such as evenings or weekends. While different from polygamous working, side hustles can still:
- Affect performance
- Raise confidentiality risks
- Spill into contracted work hours
What can employers do?
To prevent and address moonlighting:
- Screen job candidates thoroughly, including past employer references.
- Clarify policies on second jobs in offer letters.
- Ensure contracts require employees to focus on their role and include fraud prevention policies.
- Require disclosure of second jobs or include exclusivity clauses (where legally valid).
- Protect confidential information and intellectual property in contracts.
- Have open conversations about side hustles, ensuring they don’t interfere with work.
- Investigate suspected polygamous working and distinguish between dishonesty and financial desperation.
- Be cautious with monitoring tools, considering data protection and employee privacy.
Philip McCabe 3rd June 2025