Tenn. Code Ann. § 68-135-105

Each license granted under this part shall expire on March 31 following its issuance or renewal and shall become invalid on such date unless renewed. Renewal may be effected at any time during the month of March by the payment of the fee prescribed in this part; provided, that the applicant has complied with the insurance requirements. It is the duty of the state fire marshal to notify every person licensed under this part of the date of expiration of such licensed person's license and the amount of the fee required for renewal for one (1) year, such notice to be mailed at least one (1) month in advance of the date of expiration of the license.