The FLSA defines the term "employ" to include the words "suffer or permit to work". Suffer or permit to work means that if an employer requires or allows employees to work, the time spent is generally hours worked. Under the FLSA all time “worked” is compensable.

Thus, time spent doing work not requested by the employer, but still allowed, is generally hours worked, since the employer knows or has reason to believe that the employees are continuing to work and the employer is benefiting from the work being done. This time is commonly referred to as "working off the clock" and results in upaid wages for employees. For example, an employee may voluntarily continue to work at the end of regular working hours. He or she may need to finish an assigned task, prepare reports, finish waiting on a customer or take care of a patient in an emergency. Unpaid work time is a serious problem. An employee may take work home to complete in the evening or on weekends to meet a deadline. Other examples of time that may or may not be considered hours worked under the FLSA are as follows.

• Pay for Rework
• Pay for Waiting for work
• Place of work
• Meal periods and rest breaks
• Pay for Civic or Charitable work
• Volunteers
• Pay for Daylight savings time
• Pay for Dispute resolution
• Pay for Physical Exams, Fingerprinting and drug testing
• Holidays vacations or sick leave
• Pay for Homeworkers
• Lectures, meetings and training programs
• Pay for Medical attention
• National Guard/Reserve Duty
• Pay for On Call Time
• Waiting Time
• Preliminary and postliminary activities
• Sleep Time
• Employees Residing on the Employer’s Premises on a Permanent Basis, for Extended Periods of Time or Working at Home
• Full-Time and Parti-Time Relief Employees of Community Living Centers and Other Similar Facilities
• Show-Up Time
• Travel Time