Sen. Kamala Harris has released 15 years of tax returns, more than any presidential candidate so far. Her campaign released returns for every year she has held elected public office, from 2004 through 2018.

Harris and her husband, Douglas Emhoff, a lawyer, reported an adjusted gross income of about $1.9 million in 2018, substantially more than the $142,000 Harris declared in 2004 when she was the district attorney of San Francisco. They paid just under $700,000 in federal taxes, a tax rate of nearly 37 percent.

Over the past five years, the couple has paid over $2.2 million in federal taxes at an average effective tax rate of about 33 percent. Harris has been filing jointly with her husband since they were married in 2014.

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Harris reported $732,500 in income from her book, "The Truths We Hold," and $412,375 in expenses for the project.

Her release comes a day after House Ways and Means Chairman Richard Neal set a new deadline for the IRS to furnish President Trump's tax returns: 5 p.m. on Tuesday, April 23. He wrote to the IRS commissioner, Charles Rettig that he was aware of the concerns about his request and the authority of the Committee to obtain Mr. Trump's tax returns. However, he said, "Those concerns lack merit."

In an interview with CBS News, one of the leading contenders, Sen. Bernie Sanders of Vermont, pledged to disclose his tax returns by Monday. Massachusetts Sen. Elizabeth Warren has already released her 2018 tax returns. She released 11 years of returns last week. Her 2018 returns revealed she and her husband, Bruce Mann, a Harvard professor, paid about $200,000 in taxes last year on an income of approximately $900,000. Warren reported an income of $176,280 from her Senate salary and approximately $325,000 from book proceeds.

Camilo Montoya-Galvez and Ed O'Keefe contributed to this report.