ated leave, except, however, a minimum of six (6) months of leave in the aggregate shall be purchased. Total buy back credit purchased shall not exceed the member’s actual City service at the time the buy back is concluded. (f) Agreement with the City Employees’ Retirement System - Buy Back Methods. A member electing to buy back credit described herein shall enter into a written agreement with the Retirement System. Such agreement shall provide that the member contribute an amount equal to the present value of the liability incurred by the System in crediting the service based upon actuarial assumptions in effect at the time the agreement is entered into or amended, and the projected retirement date contained in the agreement. Such agreement shall identify the method of payment of the additional contributions required to fund the purchased credit, which may be a specific dollar payment or percent of salary obligation. If a member elects to make the required contribution by a specific dollar payment, the payment may be made in a lump sum or in biweekly installments through payroll deduction over a period not to exceed five (5) years. If the member elects to enter into a percent of salary obligation, the member shall agree to make the contributions as a percent of salary through payroll deduction over a period extending from the date of the agreement with the Retirement System to a projected retirement date included in the agreement. (g) Termination or Completion of Agreement. A member who has entered into a buy back agreement shall complete all contributions prior to the effective date of retirement in order to receive agreed upon buy back credit. If all contributions have not been completed and the member elects to retire, the member may receive prorated buy back credit for that portion of the service which has been purchased by contributions already made and forfeit the remainder of credit covered by the agreement or may make a lump sum payment sufficient to complete the total payment covered by the agreement. In the event the member elects to retire at a later date than the age specified in the agreement after completing all payments, no adjustments shall be made in the buy back credit or the cost of such credit.