The Fact Checker, which is written by Glenn Kessler, is available online and will have an accompanying column in the newspaper.
It was started in 2008 during the presidential campaign by Michael Dobbs, but has been brought back this year with a wider focus on statements made by figures such as political candidates, government officials and the media "that cry out for fact checking".
"It's a big world out there, and so we will rely on readers to ask questions and point out statements that need to be checked," a post introducing the column said.
"As the 2012 presidential election approaches, we will increasingly focus on statements made in the heat of the presidential contest. But we will not be limited to political charges or countercharges. We will seek to explain difficult issues, provide missing context and provide analysis and explanation of various "code words" used by politicians, diplomats and others to obscure or shade the truth," the post adds.
Readers have been asked to send in suggestions on topics to fact check and tips on claims by political candidates, interest groups, and the media, and can also vote on topics they need to have addressed.
"The idea is to engage readers," national editor at the Washington Post Kevin Merida told Journalism.co.uk. "It's a way for us to be closer to the things that matter to the vast audience out there, particularly online.
"When they are trying to sift through different sites and lots of information, we can be the last sifters ... It's a place where there won't be mistakes."
The Fact Checker will also provide its own opinion on factual disputes using a "Pinocchio Test" to illustrate.