40 ILCS 5/6-209
In computing the service rendered by a fireman prior to 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 without pay which were necessary on account of disability, and (d) leave of absence during which he was engaged in the military or naval service of the United States of America. Service credit shall not be allowed for any period during which a fireman was in receipt of pension on account of disability from any pension fund superseded by this fund.
In computing the service rendered by a fireman on and 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 he was engaged in the military or naval service of the United States of America, (d) disability for which he receives any disability benefit, (e) disability for which he receives whole or part pay, (f) leave of absence, or other authorized relief from active duty, during which he served as president of The Firemen's Association of Chicago, provided that for all leaves of absence or other authorized relief under this item (f), including those beginning before the effective date of this amendatory Act of the 97th General Assembly, the fireman continues to remain in sworn status, subject to the professional standards of the public employer or those terms established in statute, (g) periods of suspension from duty not to exceed a total of one year during the total period of service of the fireman, and (h) a period of time not to exceed 23 days in 1980 in accordance with an agreement with the City on a settlement of strike; provided that the fireman elects to make contributions to the Fund for the various annuity and benefit purposes according to the provisions of this Article as though he were an active fireman, based upon the salary attached to the civil service rank held by him during such absence from duty, and if the fireman so elects, the city shall make the prescribed concurrent contributions for such annuity and benefit purposes as provided in this Article, all to the end that such fireman shall be entitled to receive the same annuities and benefits for which he would otherwise be eligible if he had continued as an active fireman during the periods of absence from duty.
In computing service on and after the effective date for ordinary disability benefit, all periods described in the preceding paragraph, except any period for which a fireman receives ordinary disability benefit, shall be counted as periods of service.
In computing service for any of the purposes of this Article, credit shall be given for any periods prior to January 9, 1997, during which an active fireman (or fire paramedic) 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 to perform his legislative duties, notwithstanding any reduction in salary for such periods and notwithstanding that the contributions paid by the fireman were based on such reduced salary rather than the full amount of salary attached to his civil service rank.
In computing service for any of the purposes of this Article, no credit shall be given for any period during which a fireman 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 fireman and not more than one year or a proper fractional part thereof of service shall be allowed for service rendered during any calendar year.
40 ILCS 5/6-209