How does it help to know anything about a President to know about his/her taxes? One would understand that by filing taxes, one is compliant with tax law; otherwise, the IRS would punish the filer. Take many well-known figures, for example. We know when they have fallen afoul of the IRS because at that level, it is public knowledge. Anything beyond illegal, is just looking for information to satiate one's gross curiosity and look for a crime.