WASHINGTON (AP) — Amazon founder Jeff Bezos paid no income tax in 2007 and 2011. Tesla founder Elon Musk’s income tax bill came to zero in 2018. And financier George Soros went three straight years without paying federal income tax, according to a report out Tuesday from the nonprofit investigative journalism organization ProPublica.

Overall, the richest 25 Americans pay less in tax — an average of 15.8% of adjusted gross income — than many ordinary workers do, once you include taxes for Social Security and Medicare, ProPublica found.

An anonymous source delivered to ProPublica reams of Internal Revenue Service data on the country’s wealthiest people, including Warren Buffett, Bill Gates, Rupert Murdoch and Mark Zuckerberg.

ProPublica compared the tax data it received with information available from other sources. It reported that “in every instance we were able to check — involving tax filings by more than 50 separate people — the details provided to ProPublica matched the information from other sources.’’

Using perfectly legal tax strategies, many of the uber-rich are able to whittle their federal tax bills down to nothing or close to it. Soros went three straight years without paying federal income tax; billionaire investor Carl Icahn, two, ProPublica finds.

A spokesman for Soros, who has supported higher taxes on the rich, told ProPublica that the billionaire had lost money on his investments from 2016 to 2018 and so did not owe federal income tax for those years.

Musk responded to ProPublica’s initial request for comment with a punctuation mark — “?” — and did not answer detailed follow-up questions.

The federal tax code is meant to be progressive — that is, the rich pay a steadily higher tax rate on their income as it rises. And ProPublica found, in fact, that people earning between $2 million and $5 million a year paid an average of 27.5%, the highest of any group of taxpayers.

Above $5 million, though, tax rates fell: The top .001% of taxpayers — 1,400 people who reported income above $69 million — paid 23%.

And the 25 very richest people paid still less.

The rich can reduce their tax bills through the use of charitable donations or by avoiding wage income (which can be taxed at up to 37%) and benefiting instead mainly from investment income (usually taxed at 20%).

ProPublica’s findings are likely to heighten the national debate over the vast and widening inequality between the very wealthiest Americans and everyone else.

President Joe Biden, in seeking revenue to finance his spending plans, has proposed higher taxes on the wealthy. Biden wants to raise the top tax rate to 39.6% for people earning $400,000 a year or more in taxable income, estimated to be fewer than 2% of U.S. households. The top tax rate that workers pay on salaries and wages now is 37%.

Biden is proposing to nearly double the tax rate that high-earning Americans pay on profits from stocks and other investments. In addition, under his proposals, inherited capital gains would no longer be tax-free.

The president, whose proposals must be approved by Congress, would also raise taxes on corporations, which would affect wealthy investors who own corporate stocks.

ProPublica reported that the tax bills of the rich are especially low when compared with their soaring wealth — the value of their investment portfolios, real estate and other assets.

ProPublica’s data “reveals that the country’s wealthiest, who have profited handsomely during the pandemic, have not been paying their fair share of taxes,” Sen. Ron Wyden, D-Ore., who leads the tax-writing Senate Finance Committee, said at the start of a hearing on the IRS’ budget with Commissioner Charles Rettig.

Wyden has proposed legislation that would tighten enforcement of tax collection against wealthy individuals and corporations that use artifices and loopholes to skirt paying taxes.

For his part, Rettig said the IRS is investigating the leak of the tax data to ProPublica and said any violations of the law would be prosecuted. ProPublica reported that it does not know the identity of the source who provided the data.

“We will find out about the ProPublica article,” Rettig said. “We have turned it over to the appropriate investigators, both external and internal.”