I have the same question regarding prepayments having nothing to do with extension and NOT in the estimated tax category. Seems like the wording can be made clear as "Payments regardless of Extension" to be flexible.
Then a follow-up question is, by specifying the payment method with a bank account in TurboTax, is IRS smart enough to charge/refund (if overpaid) whatever left after applying the payments made earlier (posted on IRS account online)?
