Tenn. Code Ann. § 6-22-125: Reversion of appropriations to general fund

At the end of each year, all unencumbered balances or appropriations in the treasury shall revert to the general fund and be subject to further appropriations. Such balances shall be considered unencumbered only when the city manager shall certify in writing that the purposes for which they were appropriated have been completely accomplished and that no further expenditure in connection with them is necessary.