Can an employer deny a request for leave when an employee cannot provide a fixed date of return?

Can an employer deny a request for leave when an employee cannot provide a fixed date of return? Providing leave to an employee who is unable to provide a fixed date of return is a form of reasonable accommodation. However, if an employer is able to show that the lack of a fixed return date causes an undue hardship, then it can deny the leave. In certain circumstances, undue hardship will derive from the disruption to the operations of the entity that occurs because the employer can neither plan for the employee's return nor permanently fill the position. If an employee cannot provide a fixed date of return, and an employer determines that it can grant such leave at that time without causing undue hardship, the employer has the right to require, as part of the interactive process, that the employee provide periodic updates on his/her condition and possible date of return. After receiving these updates, employers may reevaluate whether continued leave constitutes an undue hardship.