Hillary Clinton released her tax return for 2015 Friday, using the occasion to press Donald Trump on his refusal to release any of his.

The Democrat's presidential campaign also released 10 years of returns for her running mate, Virginia Sen. Tim Kaine.

Claiming that the two "continue to set the standard for financial transparency," Clinton spokeswoman Jennifer Palmieri accused Trump of "hiding behind fake excuses and backtracking on his previous promises to release his tax returns. He has failed to provide the public with the most basic financial information disclosed by every major candidate in the last 40 years."

Through the @HillaryClinton twitter account, the campaign also floated the possibility that Trump isn't paying any taxes.

"We don't know for sure, because he won't release his tax returns," read a graphic attached to Clinton's tweet.

Clinton's return showed that she and her husband, former President Bill Clinton, paid a 34.2 percent effective federal tax rate on total income of $10.7 million in 2015. Most of that income came from book sales and paid speeches.

Tim Kaine and his wife Anne Holton had income of $313,441 in 2015, almost all of which came from their salaries. They paid a fifth of their income in taxes to the federal government. Over the past 10 years, their effective tax rate has varied between 13 percent and 24 percent. They contributed just under 7 percent of their income to charity.

The Clintons' return shows that the couple continued to profit from book sales and speaking engagements as Hillary worked her way through the Democratic primaries. Bill earned just under $7 million speaking and consulting. Hillary, meanwhile, earned nearly $1.5 million from speaking and $3 million in book sales.

In 2015, they deducted $1,042,000 in charitable contributions, about one-tenth of their income. Of that, $1 million went to the Clinton Family Foundation and $42,000 to Desert Classic Charities. They also deducted nearly $3,000 in mortgage interest payments.