It's not that it is too complicated. It is that it is not possible. No matter what flat amount you pick there will be people whose income is less than that. I

It's not that it is too complicated. It is that it is not possible. No matter what flat amount you pick there will be people whose income is less than that. I'm assuming you meant a flat amount because the article is about a flat amount. If you actually meant a flat rate, such as 10% of income, that is feasible. However it is also pretty much pointless. Many people imagine it would vastly simplify things but the difference between a single flat rate and a bracket system is a short paragraph and a table of N lines where N is the number brackets. The complexity of the tax system is in determining what is subject to tax. To simplify the tax system you need to greatly simplify that. Once the taxable amount is determined a bracketed rate system is only trivially more complicated than a flat rate system. Great simplification of the "what is taxable" part of the system probably requires giving up using that system to incentivize things the government wants to encourage or to discourage things the government wants to discourage. So basically getting rid of most deductions and credits. Its those deductions and credits that lead to much of the complication. A deduction or credit or surtax is added to encourage or discourage something and it works for a short while. Then people find ways to take advantage of this in other situations. Then regulations are updated to close off those other situations. But they also end up blocking some uses that should have been allowed, so more regulation ensue. This can go on for several rounds. Would getting rid of all that be feasible? Many, if not most, of the things the government uses the tax system to encourage or discourage are things it would still need to be able to encourage or discourage even if it could no longer use the tax system for that. It's not obvious what other methods are available that wouldn't be more intrusive than doing it through tax tweaks. And they would likely still be complicated, so we'd just be moving the complication to somewhere else. I suspect that complication comes from having a large and diverse economy--it is a complication economy which necessarily leads to complexity in regulating it.