U.S. Senator Kamala Harris and her husband reported more than $2 million in income on their 2018 federal tax return, with the vast majority stemming from her husband’s work as a partner in a law firm.

The California senator, one of 18 declared candidates for the 2020 Democratic presidential nomination, released 15 years’ worth of tax returns Sunday, dating back to when she first held elected office.

Harris and her husband, Douglas Emhoff, a partner at DLA Piper, reported taxable income of $1.8 million, including $157,352 from her Senate salary. The couple paid $697,611 in taxes this year with an effective rate of 38.4 percent. In 2017, before the Republican tax overhaul went into effect, they paid an effective tax rate of 40 percent and paid about a half-million dollars in taxes on lower income.

The couple reported more than $225,000 in state and local tax payments, but the tax overhaul capped the amount they could deduct from their federal taxes at $10,000. Emhoff did not qualify for a 20 percent deduction for pass-through business owners included in the new law because the deduction isn’t granted to law firms.

Harris is widely viewed as a top-tier contender in a large and growing Democratic field, running competitively in surveys for third place behind the much better-known former Vice President Joe Biden, who hasn’t officially announced, and Vermont Senator Bernie Sanders. She raised $12 million in the first quarter of 2019, second only to Sanders.

Harris has focused her message around progressive economics and social justice for immigrants, African Americans and the LGBT community. She has proposed cutting taxes for middle-income and low-income families by providing tax credits and direct payments to those households.

She has also proposed to pay for these tax breaks by rolling back benefits for those making more than $100,000 and to put a levy on banks with more than $50 billion in assets.

Before being elected to the Senate in 2016, Harris served as the California attorney general and as the San Francisco district attorney. She’s scheduled to campaign in the important early state of South Carolina this week.

Harris joins several other 2020 hopefuls, including Senators Elizabeth Warren and Amy Klobuchar, in releasing more than a decade of tax returns. Democrats have been using the release of their tax information to contrast with President Donald Trump, who in the 2016 campaign became the first presidential candidate in more than 40 years to refuse to release his returns.

Senator Bernie Sanders, who released only one year of returns when he ran for the Democratic nomination in 2016, has said he’ll make 10 years’ worth of returns public by April 15, the tax filing deadline. Sanders’ campaign manager Faiz Shakir said Saturday that the senator’s tax returns will be “boring.”

House Democrats have asked the IRS to hand over Trump’s tax returns, citing a 1924 law that allows the chairmen of the tax-writing committee to demand the returns of any American taxpayer. Treasury Secretary Steven Mnuchin, who oversees the agency, has asked the Justice Department to review the request, but Trump, White House officials, Republican members of Congress and the president’s lawyers have all said it would be a violation of his privacy to do so.

House Ways and Means Chairman Richard Neal has given the IRS an April 23 deadline to release the returns but the fight is expected to drag on for some time.