The TT program may compute an estimated underpayment penalty or the user can choose to skip it and let the IRS or state compute it but it is only an estimate. The fed/state have the right to compute their own penalty based on when you filed and paid ... they will mail you a bill. Read it carefully ... if you don't agree then follow the instructions on the notice.
A late payment penalty has nothing to do with when you *FILE* your taxes. It has everything to do with when you *PAY* your taxes and the date the IRS credits that payment.
Now if you filed your 2019 taxes late (which would be after July 15th, 2020) and paid the IRS after that date, then a late penalty is due. The best the TurboTax program can do is *ESTIMATE* the payment based on your actual filing date, if you actually filed after July 15th. But like I said, the actual amount of any late payment penalties and/or interest is bsaed on the tax payment date; not the filing date. Therefore once the IRS receives payment, it is customary for them to bill you separately via USPS for any additional interest and/or late payment or late filing fees that may be due. Pay them in a timely manner (by the deadline shown on the letter) and you're done. Otherwise, your nightmare has just begun.
I already have a federal & NY extensions so I did not need to use the TurboTax extension function. In the N.Y. input it asked if I had a N.Y. extension to extend the filing date but I cannot find @any input on the federal to reflect the extended due date of 10/15/20
I cannot find @any input on the federal to reflect the extended due date of 10/15/20
That is because there is no such place in the federal interview ... the only thing you would enter is if you had sent a payment with the extension ... you don't need to tell the IRS you filed one, they already know.