Tennessee Code Title 65. Public Utilities and Carriers § 65-33-104

A participating customer may withdraw from the payment-averaging program at any time by giving notice to the utility. When a customer leaves the program, the actual use by that customer up to that point shall be determined and, at the next billing date, the customer shall receive either a credit to the account or, upon written request, a payment in case of overestimated payment or shall pay the utility any amount not covered by that customer's averaged monthly payments.