Tennessee Code Title 67. Taxes and Licenses § 67-4-718

(a) The commissioner may, for good cause shown, grant not more than one (1) extension of time, not to exceed thirty (30) days, for a person liable for the business tax to file that person's tax return and pay the tax shown to be due.

(b) Requests for such extensions must be made in writing, stating why the extension is desired, signed, and be submitted before the delinquent date of the return and tax.

(c) Interest as provided in § 67-1-801 shall be added to the amount of tax due beginning from the regular statutory due date until the date the tax is paid. No penalty shall be assessed if the return is made and the full amount of taxes are paid on or before the extended due date. Any return and payment made subsequent to the extended due date shall, however, be subject to penalty without regard to the period allowed by the extension.