Tenn. Code § 17-517
Any person other than a county chairman becoming a judge after July 1, 1963, shall become a member of this retirement system as a condition of holding office as judge and shall file with the board within thirty (30) days of his date of employment written notice in such form and manner as the board shall require that he has become a judge covered by this retirement system. Any person becoming a county chairman after July 1, 1963, must file with the board within thirty (30) days of the date of his employment, or before July 1, 1972, written notice electing to become a member in such form and manner as the board shall require and any county chairman who does not apply for membership within said thirty (30) days, or before July 1, 1972, shall be deemed to have elected not to become a member and he shall not thereafter have any right to elect to become a member of this retirement system.
Any person who is a judge on July 1, 1963, may elect to participate or not participate in this retirement system, provided, however, that a judge who does not apply for membership before October 1, 1971, shall be deemed to have elected not to become a member as of July 1, 1963. Any judge on July 1, 1963, who elects to become a member as of that date shall, as a condition of becoming a member, contribute to the fund the monthly employee contributions for the period July 1, 1963, to the date of receipt by the board of his application to become a member; provided, however, that any judge on July 1, 1963, who applies for membership after October 1, 1965, shall pay to the fund interest on such monthly employee contributions from July 1, 1963, at the rate of five per cent (5%) per annum; and provided, further, that any judge on July 1, 1963, claiming prior service shall pay to the fund interest on such back contributions from July 1, 1963, at the rate of five per cent (5%) per annum; and provided, further, that any person who was a judge or chairman on November 1, 1965 and who elects to become a member before July 1, 1972, may claim and receive prior service credits by contributing to the fund an amount equal to the amount he would have contributed had he been a member, plus interest on such back contributions at the rate of five per cent (5%) per annum from the date the contribution would have been paid had he been a member. After the date of receipt by the board of his application to become a member, he shall not thereafter be eligible to continue membership or participation in any other system, except that he shall be entitled to enjoy, unimpaired, any vested benefit existing under such other system, but in such case, no periods of time on account of which such vested benefits exist shall be considered credited service under this chapter. Any judge on July 1, 1963, who elects not to become a member and is not covered then or thereafter by any other system, may apply to become a member in like manner at a subsequent date; such judge shall become a member as of the first day of the month next following the date of receipt of his application by the board.
Any judge on July 1, 1963, who as of that date had been a member of any retirement system of the state of Tennessee and who prior to that date had withdrawn his contributions from said system or did not otherwise retain any vested interest in said system shall be eligible to make "supplemental contributions" to this retirement system in respect of each of the years for which he had been entitled to receive credit and for which as of July 1, 1963, he did not have any right to any benefits whether or not on account of such years. The amount of "supplemental contributions" for each year for which supplemental contributions are made shall be determined as the sum of (a) three per cent (3%) of that part of his earnings per year, based on his monthly rate of earnings on July 1, 1963, not in excess of four thousand eight hundred dollars ($4,800) and (b) five per cent (5%) of that part of his earnings per year, based on his monthly rate of earnings on July 1, 1963, that is in excess of four thousand eight hundred dollars ($4,800); provided, however, that such member shall pay to the fund interest on all such supplemental contributions at the rate of five per cent (5%) per annum. Each such year for which supplemental contributions are paid shall be considered credited service, notwithstanding any provisions in this system to the contrary. No judge shall be entitled to pay to this system supplemental contributions in accordance with this § 17-517 after October 1, 1971.
Any county judge or chairman who ceases to hold such office, for reasons other than ouster or impeachment, may elect to participate in this retirement system if he (a) is a member in this retirement system at the time he ceases to hold office, (b) has at least ten (10) years credited service in this retirement system, (c) is at least forty-five (45) years of age, (d) enters into full-time employment within these three (3) months after ceasing to hold such office with an agency entitling him to participate in a state employee's retirement system, and (e) elects to participate in this system and contributes to this system from his salary in the agency in the same manner as other members of this retirement system.
All other provisions of this title notwithstanding, any county-paid judge having sixteen (16) or more years' service on January 1, 1969, and who has reached the age of seventy (70), shall be entitled to the benefits under this retirement system.
All other provisions of this title notwithstanding any person on March 1, 1972, who as of that date is a member of any retirement system of the state of Tennessee and who prior to that date had served as county judge for ten (10) years or more and had withdrawn his contributions from the retirement system for county paid judges shall be eligible to become a member of this retirement system and shall be entitled to the amount of credited service for which he was eligible at the time of termination of membership in such system upon the repayment of his withdrawn contributions together with a payment to the state treasurer equal to four per cent (4%) of the compensation he received during the time of any prior service. Common interest shall be paid on withdrawn contributions at the rate of five per cent (5%) per annum from the time of his withdrawal of such contributions to the time of repayment of his withdrawn contributions. Common interest at the rate of five per cent (5%) per annum shall also be paid to the state treasurer on all compensation received during the time of any prior service from the dates of such service.
T.C.A. § 17-517