Until 6 months after the effective date of this amendatory Act of the 100th General Assembly, any active member of the Firemen’s Annuity and Benefit Fund of Chicago may transfer to the Fund up to a total of 10 years of creditable service accumulated under Article 4 of this Code upon payment to the Fund within 5 years after the date of application of an amount equal to the difference between the amount of employee and employer contributions transferred to the Fund under Section 4-108.6 and the amounts determined by the Fund in accordance with this Section, plus interest on that difference at the actuarially assumed rate, compounded annually, from the date of service to the date of payment.
     The Fund must determine the fireman’s payment required to establish creditable service under this Section by taking into account the appropriate actuarial assumptions, including without limitation the fireman’s service, age, and salary history; the level of funding of the Fund; and any other factors that the Fund determines to be relevant. For this purpose, the fireman’s required payment should result in no significant increase to the Fund’s unfunded actuarial accrued liability determined as of the most recent actuarial valuation, based on the same assumptions and methods used to develop and report the Fund’s actuarial accrued liability and actuarial value of assets under Statement No. 25 of Governmental Accounting Standards Board or any subsequent applicable Statement.