Sen. Bernie Sanders, who has made income inequality a hallmark of his presidential campaign, earned with his wife about $566,000 last year and $1.15 million in 2017, putting them in the nation’s highest income brackets, according to tax returns released by the presidential candidate Monday.

Sanders (I-Vt.) and his wife were in the top 1 percent of all taxpayers for those two years, according to an Internal Revenue Service calculation that said such people had an adjusted gross income of $480,000 or higher. By comparison, the average income for an American household in 2018 was $62,175, according to an analysis by Sentier Research.

Sanders’s annual Senate salary is $174,000. Much of his income came from books he has written about his democratic socialist platform, which includes a call for higher taxes on the wealthiest Americans.

He has become wealthier, in part, by cashing in on his status as a presidential candidate. In 2014, before his first presidential run, he reported an income with his wife of about $206,000, according to his tax returns.

Since then, he has written two campaign-oriented books: “Our Revolution” in November 2016 and “Where We Go From Here” in November 2018. The impact of his book contracts is most evident in Sanders’s return for 2017, when he and his wife reported wages of $139,549 and business income — most of it from books — of $961,784.

That squares with a financial disclosure report that Sanders filed last year as a senator and that showed he earned $880,000 in royalties from book deals.

The 2018 returns show that Sanders and his wife, Jane, contributed about $19,000 to charity out of their income of $566,000, or 3.35 percent. The couple gave $36,300 to charity in 2017. The Sanders campaign said those rates do not reflect charitable proceeds given from one of his books, which he did not deduct from his taxes. The campaign did not say how much was given in that case.

“These tax returns show that our family has been fortunate,” Sanders said in a statement. “I am very grateful for that, as I grew up in a family that lived paycheck to paycheck and I know the stress of economic insecurity. . . . I consider paying more in taxes as my income rose to be both an obligation and an investment in our country.”

The Sanders campaign said in a news release that he paid a 26 percent effective tax rate in 2018.

Speaking at a Fox News Channel town hall Monday night, Sanders sought to downplay his wealth. “You raised the issue. I am a millionaire,” Sanders told a questioner, making air quotes as he spoke. “Well, actually, this year we had $560,000 in income.”

Daniel Shaviro, a New York University School of Law professor of taxation who examined the 2018 return at the request of The Washington Post, said the return was straightforward.

“He didn’t do a whole lot, economically or tax-wise, other than earn his Senate salary, Social Security income and book royalties, as well as paying state and local taxes and giving about $19,000 to charity,” Shaviro said. “This clearly is not the tax return of someone who does either a lot of tax planning or complex investing.”

The earliest return released Monday, for 2009, was done by hand, which may indicate that the couple did the taxes themselves. It showed they had total income of $314,742. All of the other returns have typed entries.

There is no requirement that presidential candidates release their tax returns, but many have done so by tradition. Sanders faced pressure to release his returns this year as Democrats have increasingly made an issue of President Trump’s refusal to release returns.

Trump said during the 2016 campaign that he would release his returns after an audit was completed. But after the House Ways and Means Committee recently requested them, Trump’s acting chief of staff, Mick Mulvaney, said earlier this month that Trump would “never” turn them over.

Sanders’s personal wealth has come under heightened scrutiny in recent weeks. At a Saturday campaign stop in Gary, Ind., a reporter asked Sanders whether his millionaire status was at odds with his populist economic message.  

“I don’t think so,” Sanders replied. “I didn't know it was a crime to write a good book.”

As a senator, Sanders has been required to release a financial disclosure statement, but the information in that is much more limited than a tax return. For example, the disclosure form requires that income and debts be described only in wide ranges and does not report the value of real estate.

Sanders and his wife, Jane, have three homes, one in Burlington, a second in Washington and a third, on a Vermont lakefront. Sanders was first elected to the Senate in 2006 and served in the House for 16 years before that.

Former New Hampshire Democratic Party chair Kathy Sullivan said that while she does not see a problem with Sanders’s financial status squaring with his commitment to curbing income inequality, she was struck by the way he handled questions about his wealth. “I don’t think it’s a problem that someone has been successful in the private sector,” said Sullivan, who supported Hillary Clinton in the 2016 primary. “He seemed defensive about it, and I don’t think he should be.”

The perception of a contrast between Sanders’s wealth and his rhetoric has become a campaign issue on the left and the right. Fox News mocked him on its website in a February report headlined: “Lifestyles of the rich and socialists: Bernie Sanders has 3 houses, makes millions.”

The website ThinkProgress earlier this month posted a video about what it called “Bernie’s millionaire problem.” It included clips of Sanders criticizing the influence of “millionaires and billionaires” alongside a chart showing how he became a millionaire through his book sales.

ThinkProgress is affiliated with the Center for American Progress, a liberal group, but says it is editorially independent. Sanders on Saturday said he was subject to a “smear” by the group.

Jodi Enda, the editor in chief of ThinkProgress, said in an interview that the Center for American Progress does “not see the stories until they are online” and had nothing to do with the video.

“Nobody was trying to attack him,” she said. “We were just stating the facts.” She said the video would remain online.

Neera Tanden, president of the Center for American Progress and a former adviser to Clinton, said in a statement that the video was “overly harsh.”

A number of Democratic presidential candidates have released tax returns in recent weeks. Sen. Kamala D. Harris (D-Calif.) on Sunday released 15 years of returns, showing she and her husband earned about $1.9 million in adjusted gross income in 2018. Sen. Elizabeth Warren (D-Mass.) earlier this month released a tax return that showed she and her husband earned about $906,000 in 2018. Sen. Amy Klobuchar (D-Minn.) released 12 years of tax returns, showing that she and husband earned about $292,000 in 2017. Sen. Kirsten Gillibrand (D-N.Y.) and her husband earned about $215,000 in 2018.

Gov. Jay Inslee (D) of Washington released 12 years of tax returns, showing that he and his wife earned $202,912 last year.