If I owe an underpayment penalty, is that included in what turbotax calculates that I owe in federal taxes, or do I need to go to the IRS separately to pay that?

[BMcCalpin · Accepted solution]

If an underpayment penalty is calculated on your tax return, it will be added to the other taxes and netted against your payments.

The underpayment penalty appears on line 24 of the 1040, and it is added by TurboTax into the amount due on line 23 or netted against the amount overpaid on line 20.

[Edited 3/31/2020 2:04 pm CDT - updated for 2019]