As the former president’s lawyers have explained, Trump operated his businesses almost exclusively through sole proprietorships and closely held partnerships. This makes his personal returns inordinately large and complex.

What’s important?

Some details about Trump’s taxes have managed to get into the public domain but critical pieces of the puzzle remain missing.

Essentially, what is missing is the big picture.

In September 2020, the New York Times published some data from Trump’s tax returns spanning more than 20 years. The paper said that Trump paid only $750 of taxes in 2016 and 2017. The paper said Trump paid no taxes for ten of the 15 years they analyzed.

The Times also had a expose in 2018 about how Trump received millions of dollars from his father’s real estate empire through tax deductions and maneuvers.

See also: The fight for Trump’s tax returns is over, but it could rev up the fight over IRS funding

What experts will focus on?

Individuals who own “pass through” companies can deduct their businesses’ losses from their personal returns. The Times report showed that Trump took advantage of this tax rule.

Steven Rosenthal, a senior fellow at the Tax Policy Center, told Congress that experts are wondering if Trump’s businesses losses are fair.

So far there has been no evidence that Trump violated the law, Rosenthal testified.

“But Trump stretched it beyond recognition to omit income,” he added.

In addition, Trump often portrayed himself as one of the richest American businessmen but his tax payments are a small fraction of the average $8 million paid in 2017 by the top category of tax payers.

The documents could also reveal information about the sources of Trump’s income and about his use of tax-planning strategies, said Andrew Schmidt, a professor of accounting and tax at North Carolina State University. Information on offshore companies and foreign bank accounts may be revealed.

Read: What could be learned from Trump’s tax returns?