Tenn. Code Ann. § 52-2-901: Charges for services

(a) The commissioner, in consultation with the comptroller of the treasury and with the approval of the commissioner of finance and administration, may establish by rule a method for determination at least annually of charges for services and supports provided to persons supported in programs operated by the department, including the charges for all institutional or professional services.

(b) Charges must be calculated using generally accepted accounting principles.