Fitness-for-Duty testing is a broader evaluation of whether an employee can safely perform their role, typically triggered by concerns about capability or regulatory requirements.
Return-to-Duty testing is more specific: It applies to employees coming back from leave, often following an injury, a medical absence, or a drug or alcohol program. In short, Fit-for-Duty asks whether an employee is currently fit to work, while Return-to-Duty confirms a returning employee is ready to resume their safety-sensitive duties.