40 ILCS 5/5-212
In computing the service rendered by a policeman prior to the effective date, the following periods shall be counted, in addition to all periods during where he performed the duties of his position, as periods of service for annuity purposes only: all periods of (a) vacation; (b) leave of absence with whole or part pay; (c) leave of absence without pay on account of disability; and (d) leave of absence during which the policeman was engaged in the military or naval service of the United States of America. Service credit shall not be allowed for a policeman in receipt of a pension on account of disability from any pension fund superseded by this fund.
In computing the service rendered by a policeman on or after the effective date, the following periods shall be counted, in addition to all periods during which he performed the duties of his position, as periods of service for annuity purposes only: all periods of (a) vacation; (b) leave of absence with whole or part pay; (c) leave of absence during which the policeman was engaged in the military or naval service of the United States of America; (d) time that the policeman was engaged in the military or naval service of the United States of America, during which he was passed over on any eligible list posted from an entrance examination, due to the fact that he was in such military or naval service at the time he was called for appointment to the Police Department, to be computed from the date he was passed over on any eligible list and would have been first sworn in as a policeman had he not been engaged in the military or naval service of the United States of America, until the date of his discharge from such military or naval service; provided that such policeman shall pay into this Fund the same amount that would have been deducted from his salary had he been a policeman during the aforementioned portion of such military or naval service; (e) disability for which the policeman receives any disability benefit or compensation under the Workers' Compensation Act or the Workers' Occupational Diseases Act; (f) disability for which the policeman receives whole or part pay; (g) service for which credits and creditable service have been transferred to this Fund under Section 9-121.1, 14-105.1 or 15-134.3 of this Code; and (h) periods of service in the military, naval, or air forces of the United States entered upon before beginning service as an active policeman of a municipality as provided in Section 5-214.3.
In computing service on or after the effective date for ordinary disability benefit, all periods described in the preceding paragraph, except any such period for which a policeman receives ordinary disability benefit, shall be counted as periods of service.
In computing service for any of the purposes of this Article, no credit shall be given for any period during which a policeman was not rendering active service because of his discharge from the service, unless proceedings to test the legality of the discharge are filed in a court of competent jurisdiction within one year from the date of discharge and a final judgment is entered therein declaring the discharge illegal.
No overtime or extra service shall be included in computing service of a policeman and not more than one year or a fractional part thereof of service shall be allowed for service rendered during any calendar year.
In computing service for any of the purposes of this Article, credit shall be given for any periods during which a policeman who is a member of the General Assembly is on leave of absence or is otherwise authorized to be absent from duty to enable him or her to perform legislative duties, notwithstanding any reduction in salary for such periods and notwithstanding that the contributions paid by the policeman were based on a reduced salary rather than the full amount of salary attached to his or her career service rank.
40 ILCS 5/5-212