USA TODAY

President Trump has refused to release his tax returns, bucking tradition going back four decades. But on Tuesday night, MSNBC announced that it had a copy of the president's 1040 form from 2005.

Here's what we know (and what we still don't know) about Trump's tax returns:

Has Trump released any tax information?

The White House confirmed Tuesday that Trump paid $38 million in federal income tax in 2005, after having an income of $150 million.

During the campaign, Trump said he will release his taxes once the IRS is done auditing his current return. The IRS says that they have no prohibition on Trump from releasing the information. He has released a financial disclosure form — the same form all candidates for federal office have to file — but that only lists assets and income in broad categories.

Despite winning the election and assuming office, the president has still not released returns.

What did MSNBC report on Tuesday?

MSNBC said Tuesday it had obtained part of Trump's 1040 form from 2005. The form was given to financial journalist and Trump biographer David Cay Johnston. Johnston said he received them in the mail.

The amount of federal income tax paid and the income included in the documents was confirmed by the White House. According to MSNBC, the president included $103 million in deductions.

What else is out there?

The only other released information came in October, when The New York Times obtained three pages from Trump's 1995 tax forms. They showed the top pages of Trump's tax filings for Connecticut, New Jersey and New York, all states where he earned money and paid taxes. The forms showed that Trump reported losing $913,765,884 in 1995. Tax experts questioned by the Times said Trump could have used legal tax policies to avoid paying income tax for 18 years.

What do we not know?

The forms obtained by MSNBC and Johnston do not include Trump's 2005 schedules, which would detail his sources of income and show how much he donated to charity that year.

We don't know anything about his holdings and ownership positions, his foreign income, his tax rates for any other year and any tax loopholes he may have used.

So why is there so much scrutiny to begin with?

That's pretty much what Trump's supporters ask. Surrogates say the 1995 tax documents prove that Trump is a sharp businessman, taking full advantage of the tax laws for the benefit of his companies and employees. Trump himself said he knows the tax code better than anyone else and thus is best qualified to fix it.

Trump's opponents have a different take: They argue that Trump was making millions of dollars and then using convoluted loopholes to avoid paying even as much in taxes as a regular working American family. More than 1 million people have signed a petition on the White House web site that calls on Trump to release his tax returns.

Is there other evidence that Trump did not pay?

There have been spotty stories over the years about Trump avoiding taxes in specific circumstances. For example, Politico reported in 2016 that Trump had paid no taxes for two years in the early 1990s because of significant losses in his casino operations. “Welcome to the real estate business,” Trump responded to Politico.

A USA TODAY analysis of court records in 2016 also indicated that Trump’s businesses have been involved in at least 100 lawsuits and other disputes related to unpaid taxes or how much tax his businesses owe.