(a) In order to become effective, an election to retire under the calculation provisions of either article 14 or article 15 must be made on form prepared by the Retirement System for such purpose, and timely filed with the Retirement System, as provided in below. Such form must be signed by the member or an individual authorized by law to execute a retirement option on behalf of the member, and such signature must be acknowledged. The executed and acknowledged form must be filed with the Retirement System no later than the 60th day following the effective date of retirement. Once an election has been made by the filing of a completed form, such election may only be changed on or before the 60th day following the effective date of retirement, and such a change may only be accomplished by the filing of another such form, on or before the 60th day following the effective date of retirement. The last timely election filed pursuant to this Part shall become irrevocable on the 60th day following retirement.

(b) Notwithstanding the above, an election will be considered timely filed if filed no later than 14 days following the Retirement System's issuance of a retirement estimate.

(c) In the event that the member shall not have timely filed such an election, service or vested retirement benefits, as appropriate, shall be payable pursuant to the provisions of article 15 of the Retirement and Social Security Law.