Tennessee Code Title 28. Limitation of Actions § 28-2-111

(a) Liens on realty, equitable or retained in favor of vendor on the face of the deed, also liens of mortgages, deeds of trust, and assignments of realty executed to secure debts, shall be barred, and the liens discharged, unless suits to enforce the same be brought within ten (10) years from the maturity of the debt.

(b) Subsection (a) shall not apply to lands sold for school purposes, whereon liens have been retained for the payment of the purchase money, nor to persons under disability, until three (3) years after the removal of the same.

(c) Original liens on realty retained in favor of vendors on the face of a deed, also original liens of mortgages, deeds of trust, and assignments of realty executed to secure debts, may be extended without their priority or legal effectiveness being in any way impaired, for any period of time agreed upon and beyond the ten-year period from the maturity of the obligation or debt, as provided for in subsection (a); such extension shall be evidenced by a written instrument, which shall, prior to or within ten (10) years from the maturity of the obligation or debt, be duly executed and acknowledged and be filed for record with the register of the county in which the realty affected is located and be there recorded, all in accordance with the statutes of this state in that regard; and when so filed for record such instrument of extension shall be constructive notice to all persons, as provided by the registration laws of this state; and such instrument shall contain a brief recital of the facts with reference to the original lien and shall provide that the lien shall continue, for a definite period of time in the future, to secure the remaining obligation or debt due under and secured by the original lien, and it shall not be necessary that there be any increase or decrease in the terms of the original obligation either of principal or interest.