Mister Bill's fortune is put at 47 billion dollars (38.9 billion euros), according to the latest list of the world's rich published by Forbes magazine.

At Yahoo News there is an article entitled "Microsoft founder too rich for tax computer to handle" about Mister Bill fortune. Bill Gates said at a Microsoft conference held in Lisbon:

My tax return in the United States has to be kept on a special computer because their normal computers can't deal with the numbers.
...
So I am constantly getting these notices telling me I haven't paid something when really it is just on the wrong computer.
...
Then they will send me another notice telling me how bad they feel they that they sent me a notice that was a mistake.

For me, my tax can be computed with Google calculator or just mentally. My annual income is the price of a cup coffee for Mister Bill I guess.