A business is considered to have fewer than 500 employees if, at the time an employee’s leave is to be taken, the business employs fewer than 500 full-time and part-time employees within the United States, which includes any State of the United States, the District of Columbia, or any Territory or possession of the United States. The DOL guidance provides a more detailed summary of which workers must be taken into account for purposes of the fewer than 500 employee threshold. DOL guidance also explains when business entities should be treated as separate employers and when they should be aggregated as a single employer for purposes of determining their total number of employees.