Reading through this thread, there is a poster who has repeatedly said that Line 11 col a, not including 2020 overpayment is correct. Something about you should have filed Form 4868 for it to be credited for 4/15/21 (But I filed on time without an extension, I never filed a Form 4868). Nonetheless, the fact that Turbotax has not fixed what most consider a bug, does this give credence to this user's interpretation? I read the instructions for line 11 for Form 2210 and it says "generally, consider 2020 overpayment applied to 2021 as paid on April 15th". I haven't tried selecting Box D), the poster's other suggestion, i.e., treating your withholding as paid on the dates withheld instead of equal amounts, because I didn't think it applied to my overpayment, and besides the program is not crediting my overpayment at all, on any column of line 11, it's not divvying it up into equal amounts.
