So despite Trump’s statements to the contrary, here are some general questions that a full release of at least several years of his tax returns might usefully answer:

1) Income: Trump has made the size of his fortune a centerpiece of his presidential campaign, implying that it’s a measure of his success as a businessman. He has also correctly noted that the income shown on his tax returns isn’t a reflection of his total wealth. Even so, income is a basis for assessing some of the foundations of any individual’s wealth — and would certainly reflect the financial wherewithal of the businesses in which Trump is involved.

After Fortune’s Shawn Tully dug into Trump’s financial disclosures with the Federal Election Commission and an accompanying personal balance sheet his campaign released, he noted in March that Trump “appears to have overstated his income, by a lot, which could be the reason he has so far tried to avoid releasing his returns.” Tully said that Trump apparently boosted his income in the documents by conflating his various businesses’ revenue with his personal income. Trump didn’t respond to Tully’s assessment, but he could clear up all of that by releasing his tax returns.