Tax returns don't really show much. That's been President-elect Donald Trump's story since the beginning of his run for the presidency and he is still sticking to it. "You learn very little from tax returns," said Trump, in response to reporter questions at his first post-election press conference Jan. 11.

There's no question that this ongoing assertion by Trump about the unimportance of tax returns has gotten, and held, the attention of many accountants and financial advisors who've long presumed the opposite — regardless of whether they lean red or blue.

Therefore, I thought it might be helpful to combine my experience with that of a few close colleagues in search of an answer to the objective, nonpolitical question: What exactly can — and can't — you learn about a person from his or her tax return?

A comprehensive review would be enough to put anyone to sleep, so we narrowed it down to four categories of information likely the most applicable to the majority of taxpayers: what people earn in income, what they own, what they save and what they give.