Section 40 ILCS 5/14-122 - Limitation on widow's and survivors annuity(a) If a beneficiary also qualifies for a widow's annuity or survivors annuity under Articles 2, 15, 16, 17 or 18 of this Code, and the combined annuities payable thereunder to a widow's annuity or survivors annuity beneficiary, because of established pension credits, exceed the highest annuity to such a beneficiary under the aforesaid Articles, the annuity payable by this system to the eligible beneficiary shall be reduced to an amount which when added to the annuity payable by such other system or systems would equal such highest annuity.(b) If any of the other retirement systems involved provide for a similar adjustment, the respective annuities shall be reduced in proportion to the ratio which the amount of each proportional annuity bears to the aggregate of all proportional annuities.(c) In the event a beneficiary of such other system or systems elects to waive a widow's or survivors annuity in favor of a lump sum or death benefit payment, this system shall, for the adjustment of the widow's or survivors annuity under this section, assume that the beneficiary had been entitled to an annuity as an actuarial equivalent at the date of death of the member or annuitant of such lump sum or death benefit payment as of attained age of the beneficiary at such date according to the actuarial tables in use by the system.