40 ILCS 5/16-118: Retirement.

"Retirement": Entry upon a retirement annuity or receipt of a single-sum retirement benefit granted under this Article after termination of active service as a teacher.

(a) An annuitant receiving a retirement annuity other than a disability retirement annuity may accept employment as a teacher from a school board or other employer specified in Section 16-106 without impairing retirement status, if that employment:

(1) is not within the school year during which service was terminated; and

(2) does not exceed the following:

(i) before July 1, 2001, 100 paid days or 500 paid hours in any school year;

(ii) during the period beginning July 1, 2001 through June 30, 2011, 120 paid days or 600 paid hours in each school year;

(iii) during the period beginning July 1, 2011 through June 30, 2018, 100 paid days or 500 paid hours in each school year;

(iv) beginning July 1, 2018 through June 30, 2029, 120 paid days or 600 paid hours in each school year, but not more than 100 paid days in the same classroom;

(v) (blank); and

(vi) beginning July 1, 2029, 100 paid days or 500 paid hours in each school year.

Where such permitted employment is partly on a daily and partly on an hourly basis, a day shall be considered as 5 hours.

(b) Subsection (a) does not apply to an annuitant who returns to teaching under the program established in Section 16-150.1, for the duration of his or her participation in that program.