"Salary":
An active or former policeman who (1) either retired between July 1, 1994 and December 31, 1997, both inclusive, or attained or will attain age 50 and 20 years of service between July 1, 1994 and January 1, 2002, both inclusive, and (2) received a duty availability allowance at any time after June 30, 1994 and before January 1, 1998 may elect to have that duty availability allowance included in the calculation of his or her salary under subsection (d) for all or any portion of that period for which the allowance was received, by applying in writing and paying to the Fund, no earlier than January 1, 1998 and no later than July 1, 1998, the corresponding employee contribution, without interest. Thereafter the City shall make its corresponding contribution, without interest.
This subsection (f) applies without regard to whether the applicant terminated service or began to receive a retirement annuity before the effective date of this amendatory Act of 1997. In the case of a person who is receiving a retirement annuity at the time the application and contribution are received by the Fund, the annuity shall be recalculated and the resulting increase shall become payable on the next annuity payment date following the date the contribution is received by the Fund.
40 ILCS 5/5-114