(a) The offices of the tax commissioners, tax collectors, and tax receivers of the counties of this state are declared to be adjuncts of the Department of Revenue, such offices assisting in the returning and collecting of state taxes. All tax commissioners, tax collectors, and tax receivers and employees in their offices shall be subject to a merit system of personnel administration, as promulgated by each such office, under which all such officials and employees shall perform services on the basis of merit, fitness, and efficiency.

(b) All individuals who served as such officials and employees on or after December 1, 1956, are eligible to become members of Division A of the retirement system. Any individual who becomes such an official or employee after August 1, 1958, shall become a member of Division A of the retirement system as a condition of his employment.

(c) The official in charge of such office, if he is responsible for the payment of the employees in that office, or the governing authority of the county, if the official and the employees are paid by it, shall deduct or collect from each member the employee contributions required by this chapter and shall remit the same to the retirement system as required by regulations. The state revenue commissioner is authorized and directed to pay from the funds appropriated for the operation of the Department of Revenue, the employer contributions required by this chapter, upon receipt of an invoice from the retirement system.

(d) In addition to the regular employer contributions required by this chapter, the state revenue commissioner is authorized and directed to pay from the funds appropriated for the operation of the Department of Revenue an additional contribution, as determined by the board of trustees, in a regular monthly amount sufficient to amortize, within a period of not more than 20 years, the prior service values of such members.

(e) All tax commissioners, tax collectors, tax receivers, and the employees in their offices who were in service on or after December 1, 1956, shall be entitled to all prior service credits authorized under this chapter in the same manner as if they had been members of the retirement system on such date, provided that prior service credits shall be available only to persons who become members at the time coverage was originally extended to them. No prior service credit shall be available to a person who became such an official or employee after August 1, 1958. The value of the prior service credits under this Code section shall not be in excess of the value of 25 years of prior service.

(f) Except for those persons holding office on June 30, 1983, and except as otherwise provided by subsection (h) of this Code section, any person who becomes a tax commissioner, tax collector, or tax receiver at any time after June 30, 1983, shall be a member of the retirement system under the provisions of Code Section 47-2-334 as a condition of holding office. Any person holding office as a tax commissioner, tax collector, or tax receiver on June 30, 1983, except such officials who are then members of the retirement system and except as otherwise provided by subsection (h) of this Code section, shall have the option of becoming a member of the retirement system, and such option must be exercised by not later than June 30, 1984. Such officials electing membership in the retirement system may obtain creditable service under the retirement system for actual previous service as tax commissioner, tax collector, or tax receiver or as an employee of any such official by paying to the board of trustees the regular employer and employee contributions for each year or portion thereof claimed as previous service, with the computation of such contributions being based on the compensation of the official at the time of becoming a member of the retirement system. In addition to such employer and employee contributions, the official claiming such previous service shall pay interest at the rate of 6 percent per annum on the amount of such contributions compounded annually from the time the previous service was rendered until payment is made to the board of trustees. The payment required for such previous service shall be made to the board of trustees at the time application is made for membership in the retirement system. Except for the right to obtain creditable service for previous service as provided in this subsection, any official holding office on June 30, 1983, who elects membership in the retirement system shall be under the provisions of Code Section 47-2-334.

(g) Except for those persons in employment on June 30, 1983, and except as otherwise provided by subsection (h) of this Code section, any person who becomes an employee of a tax commissioner, tax collector, or tax receiver at any time after June 30, 1983, shall have the option, which must be exercised within 180 days after the date of employment, of becoming a member of the retirement system under the provisions of Code Section 47-2-334. Any person employed by a tax commissioner, tax collector, or tax receiver on June 30, 1983, except such employees who are then members of the retirement system and except as otherwise provided by subsection (h) of this Code section, shall have the option of becoming a member of the retirement system, and such option must be exercised by not later than June 30, 1984. Such employees electing membership in the retirement system may obtain creditable service under the retirement system for actual previous service as an employee of a tax commissioner, tax collector, or tax receiver by paying to the board of trustees the regular employer and employee contributions for each year or portion thereof claimed as previous service, with the computation of such contributions being based on the compensation of the employee at the time of becoming a member of the retirement system. In addition to such employer and employee contributions, the employee claiming such previous service shall pay interest at the rate of 6 percent per annum on the amount of such contributions compounded annually from the time the previous service was rendered until payment is made to the board of trustees. The payment required for such previous service shall be made to the board of trustees at the time application is made for membership in the retirement system. Except for the right to obtain creditable service for previous service as provided in this subsection, any person employed on June 30, 1983, who elects membership in the retirement system shall be under the provisions of Code Section 47-2-334.

(h) Notwithstanding any other provisions of this Code section, no tax commissioner, tax collector, tax receiver, or any employee of any such official shall be eligible for membership in the retirement system if such official or employee is covered or becomes covered by any other public retirement or pension system, excluding social security coverage and coverage under any county or other local retirement or pension system. The provisions of subsections (a), (c), and (d) of this Code section shall apply to any tax officials or their employees who become members of the retirement system pursuant to subsections (f) and (g) of this Code section.