How do we proceed in terminating an employee on FMLA leave?

Q: We have a full-time employee who started short-term disability in October and then went on long-term disability in December. How long do we have to keep her on our payroll as an employee? When she started her short-term disability she was not eligible for FMLA, as she had exhausted it prior to that time. Are there any steps we have to take prior to legally terminating her? – Mona, Ohio