Surprise: Warren Buffett's company owes back taxes

“We anticipate that we will resolve all adjustments proposed by the US Internal Revenue Service (“IRS”) for the 2002 through 2004 tax years … within the next 12 months,” the firm’s annual report says.

It also cites outstanding tax issues for 2005 through 2009.

Obvious question: If Buffett really thinks he and his “mega-rich friends” should pay higher taxes, why doesn’t his firm fork over what it already owes under current rates?