Not sure where this discussion about SDC is coming from. Sure, "supervision" is an element of control in the existing IR35 test, but only one element, and D&C is only one element of IR35. Without knowing the details of the review, it's difficult to comment, but this is one reason you need a reviewer that really knows their stuff (because less competent reviewers may have a tendency to be too risk averse). Again, I'm not passing comment on this particular review, just the discussion that has followed here. You need to separate IR35 and SDC in your minds, at least for now.