That's big money, but these figures come with two important caveats. First,eliminating all these tax preferences would not boost revenues as much as the numbers suggest. For instance, these calculations do not reflect how taxpayers might change their behavior if these preferences were eliminated. Treasury's estimates thus overstated how much money we could raise by eliminating preferences in the tax code. Still, even allowing for these adjustments, the sum of money at stake amounts to many hundreds of billions of dollar each year -- and comes to trillions over the next decade.