Tennessee Code Title 55. Motor and Other Vehicles § 55-4-128

(1) Given a grace period of thirty (30) days from the date fixed for issuance or renewal in which to effect necessary repairs and successfully complete the emissions test for any motor vehicle that does not successfully complete an emissions test administered prior to the date fixed for issuance or renewal, and repairs necessary to pass the test cannot be effected prior to that date;

(2) Issued an inspection certificate by the motor vehicle emissions testing authority which shall state on its face the date the emissions test was administered and failed, and that a thirty-day grace period shall apply to that motor vehicle; and

(3) The air pollution control board, created by § 68-201-104, shall promulgate rules providing conditions under which owners of motor vehicles that do not successfully complete an emissions test may apply for waivers or variances. The rules may set appropriate conditions for waivers that are consistent with federal as well as state law and consider the expenditures made by the owner in order to come into compliance.