All employees not exempted or excluded from the FLSA must be paid a minimum wage for all hours worked. 29 C.F.R. §785.5. Hours worked has been defined as “all hours that an employee is ‘suffered or permitted to work’ for the employer.” 29 C.F.R.. § 785.11. Hours worked include any time in which the employee is required to be on the employer’s premises, on duty or at a prescribed work place. 29 C.F.R. § 785.7.

Understanding the concept of “hours worked” is crucial to complying with the FLSA. According to the U.S. Supreme Court (Tn. Coal, Iron & R.R. Co. v. Muscodol Local No. 123, 321 U.S. 590 (1944)), an employee must be compensated for “all time spent in physical or mental exertion (whether burdensome or not) controlled or required by the employer and pursued necessarily and primarily for the benefit of the employer.” Working time is not limited to the hours spent in active productive labor, but includes time given by the employee to the employer even though part of the time may be spent in idleness. Some of the hours spent by employees, under certain circumstances, in such activities as waiting for work, remaining “on call”, traveling on the employer's business or to and from workplaces, and in meal periods and rest periods are regarded as working time and some are not. 29 C.F.R. § 778.223.

The courts and DOL have recognized that insubstantial or insignificant periods of time outside scheduled working hours, which may not be precisely recorded, may be disregarded in recording working time. 29 C.F.R. § 785.47. The rule applies only where a few minutes of work are involved and where the failure to count such time is due to considerations justified by “operational realities.” Such time is called "de minimis", i.e., minor or trivial. The Portal-to-Portal Act of 1947 helps clarify the working time issue.

Employees, who, with the knowledge or consent of their employer, continue to work after their shifts are over, though voluntarily, are engaged in compensable working time. The reason for the work is immaterial; as long as the employer “suffers or permits” employees to work on its behalf, overtime compensation may be due. 29 C.F.R. § 785.11. This is true whether the work takes place at the place of business or the employee’s home. For example, preliminary activities such as filling out time, material or requisition sheets; checking job locations; removing trash; and fueling cars are all compensable work if done at the employer’s behest and for the employer’s benefit. This broad definition of hours worked may require employers to compensate employees for time worked that the employer may not consider “working time,” such as waiting time, travel time, certain meals and training time.