Tenn. Code Ann. § 2-14-201: When election required

(a) If twelve (12) months or more remain prior to the next general election for members of the general assembly and the seat of a member of either house becomes vacant, a successor shall be elected pursuant to § 2-14-202(a)-(c) by the qualified voters of the district in which the vacancy occurred. The successor shall serve the remainder of the original term.

(b) If a vacancy occurs with more than two (2) years remaining in a term in the state senate, but less than twelve (12) months prior to the next general election for members of the general assembly, then a successor shall be elected pursuant to § 2-14-202(d) by the qualified voters of the district in which the vacancy occurred. The successor shall serve the remainder of the original term.