Tenn. Code Ann. § 4-31-113

The state covenants with the purchasers and all subsequent holders and transferees of bonds and notes issued by the authority pursuant to this chapter, in consideration of the acceptance of and payment therefor, the bonds and notes of the authority issued pursuant to this chapter, and the income therefrom, and all moneys received or to be received by the authority and pledged to pay or to secure the payment of such bonds or notes shall at all times be free from taxation by the state or any local governmental unit or other political corporations or subdivisions thereof, except inheritance, transfer and estate taxes.