I don't know, but I would assume so. I think most people try to pay the minimum tax they are required to, and I guess that includes Mr Buffet.
However, that's not the point. He's not saying "I want to personally pay more tax", he's saying "Why are people like me not being required to pay the same percentage tax as middle-income earners"?
However, that's not the point. He's not saying "I want to personally pay more tax", he's saying "Why are people like me not being required to pay the same percentage tax as middle-income earners"?