Amends the Illinois Municipal Retirement Fund (IMRF) Article of the Illinois Pension Code. Provides that if any annuitant under the Article must be considered a participating employee because there was not a separation from service and the participating municipality or participating instrumentality that employs or re-employs that annuitant knowingly fails to notify the Board to suspend the annuity, the participating municipality or participating instrumentality may be required to reimburse the Fund for an amount up to the total (instead of one-half of the total) of any annuity payments made to the annuitant after the date the annuity should have been suspended, as determined by the Board, less any amount actually repaid by the annuitant. Removes language providing that the provisions shall not apply if the annuitant returned to work for the employer for less than 12 months. Adds similar provisions to a provision concerning separation from service and entitlement to a retirement annuity. Effective January 1, 2024.