A taxpayer must meet these requirements. If these requirements are met, then the penalty will not begin to accrue until the day after the return was submitted. You are not required to have an extension voucher on the TNTAP system.
Here’s an example: a December filer meets the requirements for an extension on his December 2017 period. The taxpayer files the return on September 15th, 2018, but does not fully pay off the remaining liability. The first installment of penalty is charged on September 16; interest accrues from April 16.