I filed a extension for my 2021 taxes. When are they now due?

[DoninGA]

Any taxes owed on your 2020 tax return were due and payable on May 17, 2021 to avoid a failure to pay penalty.

The extension was only for filing a tax return, not for paying any taxes owed on the 2020 tax return.

[Critter-3]

The extension gives you to 10/15 to file the return.