40 ILCS 5/12-133.7
A person who is eligible for the benefits provided under Section 12-133.6 and who, if he or she had retired on or before February 29, 2004, would have been entitled to a pension equal to 80% of his or her highest average salary for any 4 consecutive years within the last 10 years of service immediately preceding February 29, 2004 without receiving the benefits provided in Section 12-133.6 may elect, by filing a written election with the Fund by January 30, 2004, to receive a lump sum from the Fund on his or her last day of employment equal to 100% of his or her salary for the year ending on February 29, 2004 or the date of withdrawal, whichever is earlier. To be eligible to receive the benefit provided under this Section, the person must withdraw from service on or after January 31, 2004 and on or before February 29, 2004. If a person elects to receive the benefit provided under this Section, his or her retirement annuity otherwise payable under Section 12-133 shall be reduced by an amount equal to the actuarial equivalent of the lump sum. If a person elects to receive the benefit provided under this Section, the resulting reduction in retirement annuity under this Section shall not affect the amount of any widow's service annuity or widow's prior service annuity under Section 12-135 or any optional reversionary annuity for a surviving spouse under Section 12-136.1.
40 ILCS 5/12-133.7