(40 ILCS 5/17-151.1)
    Sec. 17-151.1. Recovery of amount paid in error.
    (a) The Board may retain out of any annuity or benefit payable to any person any amount that the Board determines is owing to the Fund because (i) required employee contributions were not made in whole or in part, (ii) employee or member obligations to return refunds were not met, or (iii) money was paid to any employee, member, or annuitant through misrepresentation, fraud, or error.
    If the Fund mistakenly sets any benefit at an incorrect amount, the Fund shall recalculate the benefit as soon as may be practicable after the mistake is discovered. The Fund shall provide the recipient, or the survivor or beneficiary of the recipient, as the case may be, with at least 60 days' notice of the corrected amount.
    If the benefit was mistakenly set too low, the Fund shall make a lump sum payment to the recipient, or the survivor or beneficiary of the recipient, as the case may be, of an amount equal to the difference between the benefits that should have been paid and those actually paid, plus interest at the rate of 3% from the date the unpaid amounts accrued to the date of payment.
    If the benefit was mistakenly set too high, the Fund may recover the amount overpaid from the recipient, or the survivor or beneficiary of the recipient, as the case may be, plus interest at 3% from the date of overpayment to the date of recovery. The recipient, or the survivor or beneficiary of the recipient, as the case may be, may elect to repay the sum owed either directly by a lump sum payment, in agreed-upon monthly payments over a period not to exceed 5 years, or through an actuarial equivalent reduction of the corrected benefit. However, if (1) the amount of the benefit was mistakenly set too high, (2) the error was undiscovered for 3 years or longer from the date of the first mistaken benefit payment, and (3) the error was not the result of incorrect information supplied by the affected member, then upon discovery of the mistake the benefit shall be adjusted to the correct level, but the recipient of the benefit shall not be required to repay to the Fund the excess amounts received in error.
    (b) The Board and the Fund shall be held free from any liability for any money retained or paid in accordance with this Section, and the employee, member, or pensioner shall be assumed to have assented and agreed to the disposition of money due.
    (c) The changes made by this amendatory Act of the 94th General Assembly are not limited to persons in service on or after the effective date of this amendatory Act.
(Source: P.A. 102-210, eff. 1-1-22.)