Tenn. Code § 67-3-418
When an end user uses undyed diesel fuel as heating oil or for other nonhighway purposes, the end user may apply for a refund of the diesel tax imposed by § 67-3-202. The end user shall not be entitled to a refund, if the end user is a commercial carrier who used the undyed diesel fuel to produce power for a means of transportation or if any other law precludes the end user from applying for a refund. The claim for refund for the diesel tax may be filed at the end of each calendar quarter but no later than one (1) year from the date of last purchase represented in the claim. The minimum amount of such claim is two hundred fifty dollars ($250). Supporting documentation shall be submitted with the claim as the commissioner may require. If the minimum is not met in one (1) quarter then it can be attached to and used in subsequent quarters, but not to exceed two (2) years.
T.C.A. § 67-3-418