Tenn. Code Ann. § 12-3-1212

Notwithstanding any charter provision, private act, or other law to the contrary, any county, municipality, utility district, LEA in accordance with § 49-2-203(a), or other local governmental entity having centralized purchasing authority with a full-time purchasing agent is authorized, by resolution or ordinance of its governing body, to increase the threshold over which public advertisement and sealed competitive bids or proposals are required to an amount not to exceed twenty-five thousand dollars ($25,000) for nonemergency, nonproprietary purchases. At least three (3) written quotations shall be required whenever possible for purchases costing less than the bid threshold established for public advertisement and sealed competitive bids or proposals but more than forty percent (40%) of such bid threshold or some lower amount as may be established by the governing body in the resolution. Purchases of like items shall be aggregated for purposes of the bid threshold.