I think part of the issue here is a redefinition of complexity. Complexity used to mean doing many calculations by hand. Now it means collecting more and more pieces of data to enter into a computer program. With this substitution, the total time to complete taxes didn't decrease while our lack of understanding of the underlying math increased. Despite the problems it causes, I don't see us going back to simpler math because there really are benefits to some of the more complex calculations. I also don't see us getting rid of all deductions because tax deductions are one of the few levers the government has to encourage different types of behavior. That said, when we're talking tax simplification, perhaps the real factor is how many pieces of information we need to compile. Income is divided into dozens of categories which all collapse into the same equation or two. (The AMT is another example of something that is based on a reasonable idea, but became unnecessary complex) Deductions are so complex that few people can figure out all the ones they can take and the best ones to take. If deductions are designed to encourage certain behaviors, they only help if people can figure out in advance what types of actions will encourage those deductions! I think some of the frustration of doing taxes is less that the math is too hard to calculate the precise values by hand and more that it's no longer easy to say, "If I do X, my taxes will go down"