Bill Clinton's retirement benefits are expected to have cost taxpayers $8 million by the end of the year, according to a report Thursday in The Politico.

The article says, since 2001, Clinton has tapped that money for expenses such as phone bills and office rent. Politico reports that, by comparison, former President George H.W. Bush used $5.5 million in federal retirement benefits and former President Jimmy Carter used $4 million during that period.

The revelation comes after Bill and Hillary Clinton reported earning close to $110 million since leaving the White House, largely on speaking fees and book deals.

The Politico article said Clinton's greater spending is due in part to the fact that he served two terms, meaning he qualifies for a different health insurance plan than one-term presidents. It said his $3.2 million office rent tab is also high because it's in the Manhattan market.

Hillary Clinton spokesman Jay Carson told the Politico the expenses are justified, since the former president has since leaving the White House worked on the tsunami in Southeast Asia and Hurricane Katrina and worked to fight AIDS and climate change.

The figures come from congressional reports on the retirement program, which extends valuable benefits to former presidents, the Politico reported.

Click here to read the full story on Clinton's retirement package in The Politico.