WASHINGTON (Reuters) - U.S. presidential candidate Bernie Sanders, who has made income inequality a top campaign theme, had taxable income of $205,271 in 2014, putting him almost in the top 5 percent of American earners, according to the release of Friday of his federal tax return.

That figure was still far below the millions earned by his main Democratic rival, Hillary Clinton, in recent years.

Sanders and his wife, Jane, paid $27,653 in federal income taxes in 2014, an effective federal tax rate of 13.5 percent, on income of $205,271, which is their adjusted gross income before deductions. That figure is just below the $206,563 that Census data show as the lower limit for the top 5 percent of U.S. households in 2014.

But Hillary Clinton and her husband, former President Bill Clinton, had income approaching $140 million over the last eight years, according to previously released returns.

Sanders on Thursday described himself as "one of the poorer members of the United States Senate."

Median net worth among members of the U.S. Senate in 2014 stood at $2.9 million, according to the Center for Responsive Politics, a non-profit organization that tracks money in politics.

The return released on Friday does not include information on Sanders' net worth.

The return does show Sanders had federal taxable income after deductions of $140,994.

Sanders has run a populist effort, vowing to reform what he calls a "corrupt" campaign finance system reliant on millionaires and billionaires at the expense of average voters.

Clinton, in contrast, has much stronger ties to the financial system, including six-figure payments for speeches she gave to several financial institutions in recent years.

Sanders often expresses skepticism that someone with those kinds of ties can effectively overhaul banks and other institutions. Clinton says she is steadfast in her commitment to eroding income inequality and creating a safe financial system.

The two have clashed repeatedly over the topic - most recently Thursday night at a debate in the New York City borough of Brooklyn. At that event, Sanders promised to release his tax returns after Clinton raised the issue.

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"You'll get them, yes," Sanders said. "They are very boring tax returns. No big money from speeches, no major investments. Unfortunately - unfortunately - I remain one of the poorer members of the United States Senate."

Clinton has a significant lead in pledged delegates over Sanders in the race for the Democratic nomination for the November presidential election.

(Reporting by Eric Beech and Luciana Lopez; Editing by Leslie Adler)