( CNN ) -- Barack Obama and his wife released their tax returns from 2000 to 2006 on his campaign Web site Tuesday , and the Illinois senator challenged Sen. Hillary Clinton to release hers . Later , Clinton said she expected to release her tax returns `` shortly , I hope within the next week . '' Sen. Barack Obama is challenging Sen. Hillary Clinton to release her 2006 tax returns . The Obama campaign said Clinton should immediately release her 2006 return , pointing to her decision to lend her campaign $ 5 million earlier this year . The Obama camp also cited former President Bill Clinton 's $ 20 million payout from supermarket holding company Yucaipa as a reason why the couple should release the documents . The Obama campaign said that company invests in tax shelters in the Cayman Islands . Clinton has promised to release 2007 returns sometime after this year 's April 15 income tax deadline , just a few days before Pennsylvania 's April 22 primary . `` Senator Clinton recently claimed that she 's 'the most transparent figure in public life , ' yet she 's dragging her feet in releasing something as basic as her annual tax returns , '' Obama 's communications director , Robert Gibbs , said in a statement . `` Senator Clinton ca n't claim to be vetted until she allows the public the opportunity to see her finances -- particularly with respect to any investment in tax shelters . '' But Clinton made her own challenge to Obama during a press conference in Greensburg , Pennsylvania . `` I am pleased that Senator Obama has released his tax returns . I think that 's a good first step , '' she said . `` Now he should release his records from being in the state Senate and any other information that the public and the press need to know from his prior experience . '' According to the 2006 return , Obama and his wife , Michelle , earned over $ 991,000 in 2006 and paid $ 277,431 on the income . More than half of the couple 's income in 2006 -- nearly $ 507,000 -- came from royalties from his two books , `` The Audacity of Hope '' and `` Dreams From My Father . '' In 2005 , Obama earned over $ 1,210,000 from royalties , according to the couple 's returns that year . The Obamas earned nearly $ 431,000 in wages in 2006 , according to the returns . The documents do not show what Obama or his wife individually earned , but the senator 's salary was $ 165,000 that year . They also earned more than $ 51,000 from Treehouse Foods , an Illinois-based food manufacturer . Michelle Obama served on Treehouse 's board from June 2005 to May 2007 . Before 2005 , the couple had more modest incomes . Between 2000 and 2004 , they earned between $ 207,647 and $ 275,123 a year . The returns were posted just minutes after the Clinton campaign attacked Obama for not releasing them . `` In the public record , there are 20 years of Hillary 's tax returns , hundreds of thousands of pages of records from her time in the White House and countless other documents detailing her time in public life . `` Sen. Obama 's record is far more opaque . Sen. Obama has not released his tax returns , except for 2006 , '' Clinton spokesman Phil Singer said in a statement sent to reporters just as the Obama camp posted the Illinois senator 's returns online . E-mail to a friend . CNN 's Rebecca Sinderbrand and Alan Silverlieb contributed to this report .
Sen. Clinton says she expects to release the ` ` shortly '' Obama campaign releases Clinton 's 2000 - 2005 returns on Web site . Obama made nearly $ 1 million in 2005 , returns 2006 . Obama challenges Clinton to release 2006 returns .