It depends on the circumstances. If I have an accountant prepare and file my taxes, or if I use a product like Turbo Tax to prepare and file my taxes, I have given my consent to those people to have access to my tax forms. But that absolutely doesn't give them the legal right to publish those forms.
Understood. I’m thinking of a case where a public agency other than the IRS might have them. I understand state casino commissions routinely require financial disclosures from people who own casinos and/or are applying for casino licenses. I believe some of Trump’s tax information previously released by the New York Times came from his New Jersey casino license files.
Something else to keep in mind here is that we have no certainty that the 2005 tax return is accurate — even if it was prepared and filed exactly as shown. There is a chance — may even a very good chance, in the case of someone like Trump who files a very complicated return — that an amended 2005 return was later filed.