https://www.yahoo.com/news/stand-accountant-confirms-trump-claimed-001106247.html Trump did not want to reveal his tax info to those he deals with to show how badly he had done in some years. --not some conspiracy. And to think, he did not take his pay as President.
I have no idea, but no one in their right mind wants to turn over their tax info to their enemies, political or business. It could be just another fishing expedition like so many "investigations" into Trump have been so far. It would be nice if the SCOTUS now determined the Tax Return to be unconstitutional. As I have said in previous posts, an attorney years ago said that every lawyer knows the U.S. tax return is unconstitutional, as you are providing information to the government for which you can be prosecuted. He said no court has the courage to decide the matter, as they feel it would be the downfall of the government to do so...but every judge knows they should.
Clearly, the request is entirely political, albeit couched in legal issues. No good would come of his turning his tax data over to a Democrat operative, because anything that might put him in a good light would be ignored while other things will be taken out of context, exaggerated, or plain misidentified in order to hurt him politically.