> It could be improved a lot just by automatically calculating more fields, and adding more of the "worksheets" that are in the instructions into the forms so it can calculate those for you.

It already does this. The form validation checks that you have filled in the required fields and on most forms about half of the field values are not user-editable and instead auto-calculated from the other half.

It also looks for the required related forms you should have attached. The worksheets are another matter and aren't required to be attached, so they aren't part of the validation. It's assumed that you have read the instructions and done the worksheets elsewhere, although you certainly can attach them anyway.

> It already does this

For some things. But there are also several fields that could be calculated, but aren't.

> It's assumed that you have read the instructions and done the worksheets elsewhere

Yes, but it would be helpful if it had something to do the worksheets as part of the site instead of you having to do the worksheet elsewhere.