As of the 2023 tax year, no, Form 1040 is not a one-pass form. Indeed, the instructions for line 78 contain the following:Include any estimated tax penalty from line 79 in the amount you enter on line 78.https://www.irs.gov/pub/irs-pdf/...Line 78 is calculated using lines 63 and 74. Then line 79 is entered. However, if the amount on line 79 is nonzero, line 78 must now be updated, so the form cannot be one-pass. Of course, one might still anticipate this and fill in line 79 first and then use lines 63, 74, and 79 to arrive at line 78, but now this breaks the usual flow of the form (although it's possible that this is precisely what the instructions suggest, and I think IRS forms in general don't have linear flow anyway; so you have at least an undocumented line dependency on the form itself, and then at least one of nonlinear flow or multiple-pass).