40 ILCS 5/15-139
If an annuitant retires at age 60 or over and receives or becomes entitled to receive during any academic year compensation in excess of the difference between his or her highest annual earnings prior to retirement and his or her annual retirement annuity computed under Rule 1, Rule 2, Rule 3, or Rule 4 of Section 15-136, or under Section 15-136.4, for services performed after the date of retirement for any employer under this System, that portion of the monthly retirement annuity provided by employer contributions shall be reduced by an amount equal to the compensation that exceeds such difference.
However, any remuneration received for serving as a member of the Illinois Educational Labor Relations Board shall be excluded from "compensation" for the purposes of this subsection (b), and serving as a member of the Illinois Educational Labor Relations Board shall not be deemed to be a return to employment for the purposes of this Section. This provision applies without regard to whether service was terminated prior to the effective date of this amendatory Act of 1991.
"Academic year", as used in this subsection (b), means the 12-month period beginning September 1.
The total service and earnings credited before and after the initial date of retirement shall be considered in determining eligibility of the employee or the employee's beneficiary to benefits under this Article, and in calculating final rate of earnings.
In determining the death benefit payable to a beneficiary of an annuitant who again becomes a participating employee under this Section, accumulated normal and additional contributions shall be considered as the sum of the accumulated normal and additional contributions at the date of initial retirement and the accumulated normal and additional contributions credited after that date, less the sum of the annuity payments received by the annuitant.
The survivors insurance benefits provided under Section 15-145 shall not be applicable to an annuitant who resumes his or her status as a participating employee, unless the annuitant, at the time of initial retirement, has a survivors insurance beneficiary who could qualify for such benefits or the annuitant repaid the survivors insurance contribution refund or additional annuity under subsection (c-5) of Section 15-154.
If the participant's employment is terminated because of circumstances other than death before 9 months from the date of reemployment, the provisions of this Section regarding resumption of status as a participating employee shall not apply. The normal and survivors insurance contributions which are deducted during this period shall be refunded to the annuitant without interest, and subsequent benefits under this Article shall be the same as those which were applicable prior to the date the annuitant resumed employment.
The amendments made to this Section by this amendatory Act of the 91st General Assembly apply without regard to whether the annuitant was in service on or after the effective date of this amendatory Act.
40 ILCS 5/15-139