Tenn. Code § 8-4019
Any county official who participates in the retirement system may designate in writing a beneficiary or beneficiaries to receive after said county official's death the retirement benefits he or she would have received for the minimum period or the remainder of the minimum period. Said designation shall be filed with the retirement board. If a county official dies during a term he is serving and at the time of death has sufficient service to qualify for retirement benefits, his beneficiary or beneficiaries, if named, shall be entitled to the same retirement benefits that the deceased county official would have received, for the minimum period only, had he or she retired on the date of death. In the event no beneficiary or beneficiaries are named, or in the event the named beneficiary or beneficiaries predeceased the county official, the system actuary shall determine the actuarial equivalent of the minimum retirement period of ten (10) years and the same shall be paid to the county official's estate in a lump sum. In the event a county official has completed twelve (12) years of service and becomes deceased before reaching the age of fifty-five (55) years, the ten (10) year minimum retirement benefits shall be paid in accordance with the provisions of this section in the same manner as they would have been paid had the county official been fifty-five (55) years of age on or before becoming deceased, provided further, that in the event a county official under the age of fifty-five (55) years is not reelected to his or her office, then upon reaching the age of fifty-five (55) years, said person shall be entitled to receive benefits as provided by this act if said county official has met all other requirements as to years of service and personal contributions herein provided, and this section shall have effect notwithstanding the provisions of §§ 8-4014, 8-4015 and 8-4018.
T.C.A. § 8-4019