Under the Workforce Innovation and Opportunity Act (WIOA), an incumbent worker is an individual who is already employed by the same employer, has an established employer–employee relationship, and has worked for that employer for at least 6 months (with some exceptions for training cohorts).

Incumbent worker training refers to training designed to help retain or advance existing employees by improving their skills, often to prevent layoffs or support promotions.  They may or may not be eligible for other adult or dislocated worker programs, unless they also participate in those.