Additional optional contributions for the alternative annuity shall be as follows:
The plan of optional alternative benefits and contributions shall not be available to any former city officer or employee receiving an annuity from the Fund on the effective date of the plan, unless he re-enters service as an elected city officer and renders at least 3 years of additional service after the date of re-entry. However, a person who holds office as a city officer on June 1, 1995 may elect to participate in the plan, to transfer credits into the Fund from other Articles of this Code, and to make the contributions required for prior service, until 30 days after the effective date of this amendatory Act of the 92nd General Assembly, notwithstanding the ending of his term of office prior to that effective date; in the event that the person is already receiving an annuity from this Fund or any other Article of this Code at the time of making this election, the annuity shall be recalculated to include any increase resulting from participation in the plan, with such increase taking effect on the effective date of the election.
40 ILCS 5/8-243.2