Tenn. Code Ann. § 33-2-1101: Calculation of charges for service

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

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