Tenn. Code § 56-7-2204
For the purposes of this part, companies that are affiliated companies or that are eligible to file a consolidated tax return shall be treated as one (1) carrier, except that with respect to affiliated companies, all of which are in existence and affiliated on January 1, 1992, the group of affiliated companies is considered to be one (1) carrier only after one (1) member of the group transfers any small employer business to another member of the group, and except that any insurance company, hospital service plan or medical service plan that is an affiliate of an HMO located in this state or any HMO located in this state that is an affiliate of an insurance company, a health service corporation or a medical service corporation may treat the HMO as a separate carrier and each HMO that operates only one (1) HMO in a service area of this state may be considered a separate carrier.
T.C.A. § 56-7-2204