Confidential IRS records outlining some of the world's wealthiest individuals in the United States were published to ProPublica earlier today.
The IRS has launched an investigation into how the company obtained the private documents.
IRS Commissioner Charles Rettig revealed the proper authorities are investigating the tax data leak.
"We have turned it over to the appropriate investigators, both external and internal," Rettig said on Tuesday.
The FBI, D.C.'s US Attorney's Office, and the Treasury's Office of the Inspector General are all reportedly on the case.
"The unauthorized disclosure of confidential government information is illegal," a spokesperson for the Treasury Office stated.
According to ProPublica's documentation, Bezos -- known for founding Amazon -- paid no income tax in 2007 and 2011.
Musk -- who founded Tesla, SpaceX, and a slew of other successful ventures -- paid $0 in income taxes for the 2018 year.
While Bezos and Musk are among the highest-profile names, they are not alone.
Investor George Soros -- who's worth an estimated $8.6 billion -- reportedly did not pay income tax for three years straight.
Another investor Carl Icahn allegedly didn't pay federal tax in 2016 and 2017. He's reportedly worth a whopping $14.9 billion.
ProPublica also shared a "true tax rate" for the billionaires, comparing what they paid in taxes annually during a four-year period and what Forbes alleged they were worth.
The site discovered that the 25 wealthiest Americans pay less in tax than the average Joe does.
According to the leaked documents, Bezos' wealth grew substantially compared to what he allegedly reported.
ProPublica claims his estimated worth is $99 billion but his total reported income was listed as $4.22 billion between the years of 2014 and 2018.
Musk's wealth ballooned to an estimated $13.9 billion between those same four years.
While the Tesla CEO paid no income tax in 2018, the leaked documents show he did pay $68,000 in 2015.
In 2017, Musk paid $65,000 in taxes.