Warren Buffet, I Love Hippocracy

“At December 31, 2010… net unrecognized tax benefits were $1,005 million”, or about $1 billion. McCarty explained, “Unrecognized tax benefits represent the company’s potential future obligation to the IRS and other taxing authorities.  They have to be recorded in the company’s financial statements.”

He added, “The notation means that Berkshire Hathaway’s own auditors have probably said that $1 billion is more likely than not owed to the government.”