Warren Buffett has a challenge to congressional Republicans who mocked him last year for criticizing the tax code. 

The billionaire investor says he'll match them dollar-for-dollar for every contribution they make to pay down the national debt. 

"And I'll even go three for one for McConnell," he said in an interview with Time magazine, referencing Senate Republican Leader Mitch McConnell

The challenge comes after McConnell suggested last year that Buffett should send Uncle Sam a check if he's feeling "guilty" about not paying enough in taxes. Buffett had complained that he enjoys a lower tax rate than his secretary, urging Congress to change the tax code so the wealthy pay more as part of a long-term deficit reduction effort. 

Until that happens, he said, "It restores my faith in human nature to think that there are people who have been around Washington all this time and are not yet so cynical as to think that (the deficit) can't be solved by voluntary contributions."