That would be an estimated tax penalty (Line 79). It is also calculated by TurboTax but depending on the amount of SE tax owed you may not owe the penalty. Also, there can be exceptions for the penalty and you can review that section under Federal Tax > Other Tax Situations > Additional Tax Payments > Underpayment penalties
Yes, the full return isn't visible until after payment. But, you can view your Form 1040 itself before payment (but not the supporting forms and schedules) if you go to My Account > Tools > View Tax Summary > click Preview my 1040 (its in the gray header). Also, if you are ever in need of wanting to check something before going all the way to the filing process you can go to My Account > Print Center and follow the prompts. The program will take your payment then and you can download the pdf of your return at that moment then. So, say you want to see your full Schedule C after you enter your business income but don't want to go through the rest of the return yet. You can use this option to pay and download the return to view the forms before filing.
