Other things are needed only if we elect to method A of calculation, but not if we use method B of calculation. So I give him all the data; he computes my obligations using method A and method B, chooses the better option, and reports only the data needed to support that method's calculations.
I pay my preparer to be an expert in tax code, to represent me in any audits, and incidentally to prepare my return correctly.
Part of that expertise is that I don't have to be an expert, so I tell him everything and he politely rolls his eyes and smiles when I dump irrelevant things on his desk.