20 ILCS 415/8a.2
For the purposes of the pay plan established under Section 8a of this Code, the Director may establish a special pay supplement for those positions of employment that require, pursuant to the Department's official classification specification, that a person employed in that position speak or write a language other than English. Positions paid under Section 8a of this Code may be eligible for a bilingual pay supplement to attract bilingual individuals, to encourage present employees to become proficient in languages other than English, or to retain qualified bilingual employees.
The positions eligible for a bilingual pay supplement, the amount of the supplement and the length of time it remains in effect shall be negotiated between the Department and the appropriate collective bargaining representative as determined under the Illinois Public Labor Relations Act. The bilingual pay supplement may be negotiated for each foreign language required for the position by the Department's official classification specification.
A bilingual pay supplement shall be processed within 30 calendar days after the employee presents to the Director, or the Director's designee for this purpose, a certification from either:
20 ILCS 415/8a.2