Tenn. Code Ann. § 55-2-101

Except as otherwise specifically provided by law, chapters 1-6 of this title shall be administered by the commissioner of revenue. The commissioner of revenue shall have the authority to delegate to the county clerks any functions and duties regarding the administration of chapters 1-6 and chapter 21 of this title; provided, however, that such authority shall not extend to the functions and duties regarding the administration of chapter 3, part 2 of this title. Such delegation shall be in a written form acceptable to the commissioner. The county clerk shall have the option of accepting or rejecting any such delegation.