I filed an extension through TurboTax and sent tax payment amount that I expected would be owed. That number was low and I owed more which TT figured the penalty owed by using the date that I entered I would pay. Coincidentally the same day I filed final tax form.
The electronic filing instructions stated pay by 4/15. This is after I filed an extension and noted paid amount then in TT, so obviously TT should have directed to pay amount noted by day that I entered I would pay (10/2), so that the penalty amount would be correct.
The bigger issue with TT though is that I was directed to send payment, even though the tax I filed through TT directed IRS to withdraw from my bank account directly.
