Involuntary Deductions associations with tax reporting unit

We have a need to associate an Involuntary Deductions card with a tax reporting unit. When trying to associate through HDL, there is an error message "You can't associate this calculation card with a tax reporting unit". We have also tried adding an additional input value ("Employer") to the State Levy component with the intent to create a FF to deduct or not based on this entry. But while you can see that new input value in element entries, there is no way to edit from the element entries screen, and this additional input value doesn't appear anywhere on the