Tennessee Code Title 6. Cities and Towns § 6-54-601

(a) Incorporated cities and towns are authorized to enter into contracts and mutual aid agreements with other incorporated cities and towns, with counties, with private incorporated fire departments, with utility districts that provide firefighting service, with metropolitan airport authorities that provide firefighting service, and with industrial fire departments to furnish one another assistance in fighting fires.

(b) Incorporated cities and towns may also enter into contracts with organizations of residents and property owners of unincorporated communities for the purpose of providing firefighting assistance to the unincorporated community.

(c) Any incorporated city or town may provide fire protection to citizens outside the territorial limits of the municipality on an individual contractual basis whenever an agreement has been made for the extension of that service by the legislative body of the municipality and the legislative body of the county in which the fire protection is to be provided. In addition, any municipality may provide fire protection to citizens within an area outside the territorial limits of the municipality without individual contracts whenever an agreement has been made by the legislative body of the municipality, and the legislative body of the county in which fire protection is to be provided for the extension of that service and establishing the area to be served. Counties may appropriate funds for the payment of compensation to the municipalities for the extension of firefighting service.

(d) Contracts or mutual aid agreements entered into pursuant to this section by an incorporated city or town shall, in the judgment of the city's or town's governing body, be advantageous to and serve the public interest of the city or town.

(e) The authority in this section for municipalities to go outside their corporate limits to provide firefighting service is in addition and supplemental to, and not in substitution for, any such authority in any other general law or in any municipality's charter.