Gillibrand releases tax returns, challenges other 2020 Democratic candidates to do the same

"I think transparency and accountability is so important in government," Gillibrand, a New York Democrat, told CNN's Alisyn Camerota on "New Day" on Wednesday. "And I think the American people have a right to know, particularly people who are running for president and are president today, who has not disclosed his tax returns."

"It allows people to know you're working for them and nobody else," she added.

Gillibrand is the first 2020 presidential candidate to disclose her 2018 tax return as Democrats have lambasted President Donald Trump for withholding his. In 2016, Trump broke with decades of tradition and refused to release his tax returns, claiming he was under Internal Revenue Service audit. Trump's decision to forgo releasing his tax returns has incensed Democrats and ethics watchdogs, who accuse the President of hiding his assets that could indicate conflicts of interest.

"And now, as we fight to defeat Donald Trump, we need honesty, transparency and accountability more than ever. That's why Kirsten has posted her tax returns from the last 12 years here for all to see. And she's calling on every candidate in the Democratic field to follow her lead and release theirs, too," her campaign website reads, along with links to her past tax returns dating back to 2007.

Massachusetts Sen. Elizabeth Warren has publicly released the past 10 years of her tax returns and has also called on "every other candidate for President to do exactly the same thing" in a tweet and online petition. She has not yet released her 2018 tax return, though the tax season ends on April 15.

Vermont Sen. Bernie Sanders recently promised to release 10 years of his tax returns, but he has not provide a timeline of when he'd do so. "Soon," he told CNN's Wolf Blitzer during a CNN town hall last month. Asked what the delay was, Sanders said, "It just was a mechanical issue. We don't have accountants at home. My wife does most of it and we will get that stuff out."

Tax returns provide a fuller picture of a presidential candidate's financial state including sources of income, the candidates' tax rate, any charitable donations or foreign accounts.

Prior to Trump, every president since Richard Nixon had released their tax returns, with the exception of Gerald Ford, who instead shared a decade's worth of summary data about his federal taxes.

Some major party candidates have released decades' worth of returns, while others have only made the top two pages of their federal Form 1040 public.

The Democratic-led House recently passed a sweeping legislative proposal that mandates the disclosure of presidential tax returns.