70 ILCS 705/16.13c
When the force of the fire department is reduced, and positions displaced or abolished, seniority shall prevail and the officers and members so reduced in rank, or removed from the service of the fire department shall be considered furloughed without pay.
If any positions which have been vacated because of a reduction in forces or displacement and abolition of positions are reinstated, such members and officers of the fire department as are furloughed from the positions shall be notified by the board by registered mail of such reinstatement of positions and shall have prior right to such positions if otherwise qualified, and in all cases seniority shall prevail. Written application for such reinstated position must be made by the furloughed person within 30 days after notification as above provided and such person may be required to submit to examination by physicians of the board of fire commissioners to determine his physical fitness.
70 ILCS 705/16.13c