The president of the United States is paid $400,000 a year while in office. They also earn a substantial pension for the rest of their life under the Former Presidents Act of 1958. But, just like most politicians, presidents don't endure the rigors of the campaign trail and put up with life as the most scrutinized leader in the world for the money. The cash really starts rolling in when commanders-in-chief leave the White House and hit the speaking circuit. America's former presidents are raking in tens of millions of dollars just by making speeches, according to tax records and published reports. They speak at corporate conventions, charity fundraisers and business conferences. You don't have to be a former president to rake in speaking fees, though. Even failed presidential candidates such as Jeb Bush, Hillary Clinton, and Ben Carson get paid tens of thousands of dollars—and in Clinton's case a couple hundred thousand dollars—per speech, according to published reports. Gerald Ford was the first to take advantage of a president's status after leaving office, according to Mark K. Updegrove, the author of Second Acts: Presidential Lives and Legacies After the White House. Ford earned as much as $40,000 per speech after leaving office in 1977, Updegrove wrote. Others before him, including Harry Truman, deliberately avoided speaking for money, saying they believed the practice was exploitative. Here's a look at how much America's four living former presidents earn on the speaking trail.

01 of 04 Bill Clinton - $750,000 Mathias Kniepeiss/Getty Images Former President Bill Clinton has made the most of any modern president on the speaking circuit. He gives dozens of speeches a year and each brings in between $250,000 and $500,000 per engagement, according to published reports. He also earned $750,000 for a single speech in Hong Kong in 2011. In the decade or so after Clinton left office, from 2001 through 2012, he made at least $104 million in speaking fees, according to an analysis by The Washington Post. Clinton makes no bones about why he charges so much. “I gotta pay our bills,” he told NBC News.

02 of 04 Barack Obama - $400,000 Pete Souza/Official White House Photo Less than a year after leaving office, former President Barack Obama came under fire from fellow Democrats when it was revealed he was being paid $1.2 million for three separate speeches to Wall Street groups. That's $400,000 per speech. The $400,000 appeared to be Obama's standard fee, as he had already been paid the same amount for a conversation with presidential historian Doris Kearns Goodwin, the U.K.'s Independent reported. But it was the coziness with Wall Street that bothered those on the left. Kevin Lewis, a spokesman for the former president, defended the speeches, saying all Obama's appearances had given him a chance to say things "true to his values." He continued: “His paid speeches in part have allowed President Obama to contribute $2m to Chicago programs offering job training and employment opportunities to low-income youth.”

03 of 04 George W. Bush - $175,000 Ronald Martinez / Getty Images Former President George W. Bush earns between $100,000 and $175,000 per speech and is considered one of the most prolific speech-makers in modern politics. The news source Politico has documented Bush's appearances on the speaking circuit and found he's been the keynote in at least 200 events since leaving office. Do the math. That amounts to at least $20 million and as much as $35 million in speaking fees he's raked in. Though it should come as no surprise given his stated intention upon leaving off to “replenish the ol’ coffers.” Politico reported in 2015 that Bush does his speaking, "in private, in convention centers and hotel ballrooms, resorts and casinos, from Canada to Asia, from New York to Miami, from all over Texas to Las Vegas a bunch, playing his part in what has become a lucrative staple of the modern post-presidency."