Tennessee Code Title 5. Counties § 5-14-202

(1) Made from county highway funds pursuant to § 54-7-113;

(2) Made from county education funds pursuant to § 49-2-203;

(3) Made by any county that has adopted either the County Purchasing Law of 1957, compiled in part 1 of this chapter, or the County Financial Management System of 1981, compiled in chapter 21 of this title;

(4) Made by any county governed by a private act regarding purchasing if such private act provides for advertisement and competitive bidding before a purchase is made and if the dollar amount for each purchase requiring advertisement and competitive bidding is ten thousand dollars ($10,000) or some lesser amount;

(5) Made under § 12-3-1201;

(6) Made by any county having a population of seven hundred thousand (700,000) or more according to any federal census and governed by a private act regarding purchasing, if such private act provides for advertisement and competitive bidding before a purchase is made and if the dollar amount for each purchase requiring advertisement and competitive bidding is five thousand dollars ($5,000) or some lesser amount;

(7) From nonprofit corporations, such as the Local Government Data Processing Corporation, whose purpose is to provide goods or services specifically to counties; or

(8) Made by a county with a population of not less than two hundred thousand (200,000) according to any federal census, so long as the county through county or metropolitan government charter, private act, or ordinance has established a procedure regarding purchasing that provides for advertisement and competitive bidding and sets a dollar amount for each purchase requiring advertisement and competitive bidding; provided, that purchases of less than the dollar amount requiring advertisement and competitive bidding shall, wherever possible, be based upon at least three (3) competitive bids.