Tenn. Code Ann. § 5-12-212

When the budget has been adopted, whether by action of the county legislative body or by operation of law, any budget amendment requested by any department to appropriate local, state or federal revenues, received in excess of the estimates used to adopt the budget, may be approved by a majority vote of the county legislative body. Notwithstanding, any department requesting such approval shall give written notice to the county mayor at least seven (7) calendar days prior to consideration of the request by the county legislative body. Other amendments shall be approved as provided in § 5-12-213.