How do I proceed if my taxes for 2016 were filed as an extension, but not on turbo tax

[Carl]

Just use turbotax and start your return "as if" you filed no extension. Then, when you get to that point under the deductions and credits tab, there's a section for Estimates and Other Taxes Paid. That's where you will enter any amount you paid at the time you filed the extension......*when you get to that point in the program*.

[fanfare]

There is nothing different about it. But if you made a payment with your form 4868 you'll have to enter it yourself.