The tax outcome of a deal, for you and for your investors, is set before you close: how the entity is structured, how depreciation is allocated, what the waterfall looks like, and how the eventual sale is anticipated. Change those after the fact and you are usually just documenting a result you no longer control.
Advisory at the structuring stage means reviewing the operating agreement for tax purposes, not just legal enforceability, and checking whether the allocations meet the substantial economic effect standard before the agreement is signed. It means asking whether a preferred return is being treated as debt or equity, and whether the partners who are absorbing depreciation losses are the ones who can actually use them. These are answerable questions, but only while the structure is still open.