Tenn. Code Ann. § 5-12-217: Creation of a revenue fluctuation major category

The county legislative body may, in its discretion and with the approval of the county mayor, county board of education, or chief administrative officer of the county highway department whose budget is affected, create a reservation of fund balance for such revenue fluctuations for any fund or funds. Such reservation of revenue fluctuations shall be available to fund shortfalls in revenue or to meet unforeseen increases in operating expenses, or both.