(a) As used in this Code section, the term:

(1) "Independent school system" means the independent school system of a municipality.

(2) "Local retirement fund" means a local retirement fund covering teachers employed by an independent school system.

(3) "Municipality" means any municipality of this state having a population of 300,000 or more according to the United States decennial census of 1970 or any future such census.

(4) "Teacher" means any teacher as defined by Code Section 47-3-1 who is employed by an independent school system.

(b) Any teacher who is employed by an independent school system after July 1, 1979, shall become a member of the retirement system as a condition of employment, and such teacher shall not be eligible for membership in a local retirement fund.

(c) Teachers who are actively employed on July 1, 1979, by an employer operating under a local retirement fund may elect to transfer from membership in the local retirement fund to membership in the Teachers Retirement System of Georgia, effective July 1, 1979. Such election must be made before July 1, 1979, in a manner prescribed by the board of trustees. All such teachers who transfer their membership to the retirement system under this Code section shall receive creditable service under the retirement system, equivalent to the creditable service such teachers had under the local retirement fund as of the date all payments are made as provided in subsections (d) and (e) of this Code section, provided that no creditable service shall be granted for service which would not otherwise be allowable under the retirement system. The board of trustees shall cause the records of such transferred teachers, after verification in the manner prescribed by the board of trustees, to reflect such creditable service.

(d) For each teacher becoming a member of the retirement system pursuant to subsection (c) of this Code section, the fiscal authority or other governing body, by whatever name designated, of the local retirement fund shall be empowered and shall have the duty to pay to the board of trustees the amount of contributions paid by such teacher to the local retirement fund and credited to each such teacher under it, together with applicable accrued regular interest, as determined by the board of trustees, to the date of payment. The fiscal authority or other governing body shall have the duty to notify the board of trustees as to the amount paid on behalf of each such teacher. Such payment shall be made to the board of trustees by not later than October 1, 1979, or by the date of retirement of any teachers who retire prior to October 1, 1979, whichever is earlier.

(e) Each teacher who becomes a member of the retirement system pursuant to subsection (c) of this Code section shall pay to the board of trustees the amount of contributions which would have been paid by the teacher to the retirement system had the teacher been a member of the retirement system during the period of creditable service established pursuant to subsection (c) of this Code section, plus interest, as provided in this subsection, which would have accumulated on such contributions, less the amount paid on behalf of each such teacher pursuant to subsection (d) of this Code section. Interest which would have accumulated on such contributions shall be computed on the basis of regular accrued interest until January 1, 1982, and on the basis of 16 percent per annum from January 1, 1982, until the payment required by this subsection is made. The board of trustees shall determine the amount to be paid as interest. Such payment shall and must be made to the board of trustees in the manner prescribed by the board of trustees by not later than December 31, 1983, or by the date of retirement for any teacher who retires prior to December 31, 1983, whichever is earlier.