Tenn. Code Ann. § 56-4-201: Companies subject to tax - "Insurance company" defined

(a) Every domestic or foreign insurance company writing life, fire, marine, fidelity, surety, casualty, liability, or other forms of insurance shall pay directly to the commissioner the taxes as provided for in this part.

(b) As used in this part, "insurance company" means any insurance, fidelity or surety company, including any corporation, company, partnership, association, society, order, fraternal or otherwise, individual or aggregation of individuals engaging in, or proposing or attempting to engage in, any kind of insurance or surety business, including the exchanging of reciprocal or interinsurance contracts between individuals, partnerships and corporations.