Tennessee Code Title 5. Counties § 5-2-115

(a) In circumstances where property is claimed to be located within the boundaries of two (2) adjoining counties and the property has been assessed for property taxation by both counties, the location of county boundaries shall be determined by the state board of equalization.

(b) If the state board determines that the entire property lies within either of the respective counties, it shall declare the assessment made by the other county void.

(c) Upon a determination by the state board that the property is partially located within the boundaries of both counties, it shall determine the number of acres or amount of property lying within each of the respective counties and determine the pro rata value of the property lying within each of the counties and assess the same pursuant to § 67-5-505.

(d) When property has been assessed in one county for five (5) years or more, the state board shall not have authority to rule that such property shall be located in a different county, but the board shall have authority to redress double assessment in these circumstances by voiding the later assessment to the extent it represents an assessment by both counties.