You would have to print and mail the Form 4868 extension request to the IRS when using the TurboTax software.
The IRS does not send a confirmation of approval but will mail you a rejection letter. So if you do not receive a rejection then the extension was approved and you can file the 2020 federal tax return at any time up through October 15, 2021.
Any federal taxes owed must be paid on or before April 15, 2021 to avoid a failure to pay penalty and interest owed on the unpaid taxes.
