Indiana Code Title 22. Labor and Safety § 22-2-13-12

Sec. 12. (a) An employee who wants to take a leave of absence under this chapter shall provide written notice, including a copy of the active duty orders if available, to the employee's employer of the date the leave will begin.  An employee shall give at least thirty (30) days notice before the date on which the employee intends to begin the leave, unless the active duty orders are issued less than thirty (30) days before the date the requested leave is to begin.

(b) An employer may require verification of an employee's eligibility for the leave.  If an employee fails to provide verification required under this subsection, an employer may consider the employee's absence from employment unexcused.