FMLA is a federal law - unpaid leave & the employee may choose, or an employer may require an employee to use any accrued vacation days or unspecified paid time off (PTO) days during the leave. Also, an employee can choose, or an employer can require an employee, to use accrued paid sick days during an unpaid FMLA leave, but only if the employee takes FMLA leave for a reason for which the employee could otherwise use sick days.