Tennessee Code Title 5. Counties § 5-16-109

(a) The board or administrative agency shall determine and fix charges to be made for furnishing any and all of the facilities as provided in this chapter, upon a basis calculated to ensure the fiscal solvency of the operation at all times.

(b) The board or administrative agency is further authorized and directed to make and publish reasonable rules and regulations covering the use by any individual, firm or corporation of any facility furnished to users.

(c) A board or administrative agency that is increasing the charges for fire protection services by more than ten percent (10%) shall obtain approval for such increase from the county legislative body prior to the increase taking effect. This subsection (c) applies in any county having a population greater than nine hundred thousand (900,000), according to the 2010 federal census or any subsequent federal census.