You can still have a tax due even though you made a payment with the extension. That was just an estimate. You still owe more. Does the extension payment show up on 1040 schedule 3 line 9. And go to 1040 line 31. If you need to enter the payment.....
You can type estimates paid in the search box at the top of your return and click Find and it will give you a link to Jump To the screen where you enter Extension Payments.
To enter the amount you paid with an extension (including state extension) go to
Federal Taxes (or Personal for desktop H&B version)
Deductions and Credits
Then scroll way down to Estimates and Other Taxes Paid
Other Income Taxes - Click the Start or Update button
Next page second section Payments with Extension
Either Visit All or Click Start or Update by the extension you paid
