Any public official authorized by local constitutional amendment to participate in the Employees’ Retirement System of Alabama and to purchase service credit in the retirement system for the time the official has served in the office he or she is holding at the time of ratification of the amendment may purchase the service credit provided such official has not previously received credit for the requested service in any other public pension fund by paying to the Secretary-Treasurer of the Employees’ Retirement System a sum equal to the total contributions which he or she would have made had he or she been authorized to participate during his or her tenure in office plus eight percent interest on such total contributions compounded annually from the date of the service. This section shall apply to local constitutional amendments ratified prior to and after July 1, 2004.