@boliver3 If you know all your other numbers and this SEHID issue is just a last thing you're trying to get "correct" then going through all the calculations one time and entering the answer makes sense. But I'm trying to use the software to test out many different Traditional contribution amounts to see how they change my overall Federal and State tax. So it would not be feasible to do all those complex PTC, repayment limit, and SHID calculations by hand over and over and over at each level. That's the exact thing I'm counting on the software for - to do those calculations so I can just plug the numbers into my own considerations to make my best choice of Traditional contribution. I think this is a very reasonable endeavor to use tax software for, yet because of this SEHID issue, I can't use TurboTax very well to do it and rely on the outcome. Especially because the place where TurboTax screws it up, right around the points where you get APTC repayment limits, are exactly the points we usually want to use Traditional contributions to get down to to take advantage of those repayment limits.
I did learn how to manually enter my own SEHID in TurboTax and, when it's obvious what it should be, I do that and then take the numbers I get using that SEHID. But wherever the SEHID isn't obvious, I'm at the mercy of TurboTax because I can't calculate it myself repeatedly given how complex it is to do.
I'm now trying some other software for comparison and they seem to do better and usually when there is an odd-man-out, it's TurboTax that doesn't agree with the others, though the others also have some issues in different aspects.
