Where can I pay my underpayment penalty?

[Vanessa · Accepted solution]

The underpayment penalty is included in your Tax Due showing in TurboTax.  Because of where the line is on the form this year, it does not appear to be included, however, if you subtract line 18 from 15 then add in line 23 you will see the penalty is included on line 22 of your 1040.

If you told TurboTax to NOT calculate the penalty for you, then you can go to Pay.gov to make the payment or wait for the IRS to send you a letter with the penalty amount due.