When you requested your extension you were supposed to pay your estimated tax due. Did you enter the payment you made into your tax return? Go to Federal>Deductions and Credits>Estimates and Other Taxes Paid>Other Income Taxes This will show up on line 17 of your Form 1040
So to clarify my situation:
1) I filed an extension for my 2018 taxes in April 2019 and paid $XX with my extension filing,
2) In May 2019 I realized that the $XX tax I paid with the extension was not sufficient.
2) So in May 2019, I sent in an additional payment of $YY to IRS.
Where do I include the $YY payment in my Turbotax filing?