Anti-tax advocates are opposed to this kind of measure for 2 reasons: 1.) If we make it easy to file taxes, that means it's less painful and makes it harder to

Anti-tax advocates are opposed to this kind of measure for 2 reasons: 1.) If we make it easy to file taxes, that means it's less painful and makes it harder to sell the cause of lower taxes as a political issue. 2.) If a citizen gets a bill from the IRS saying, "you owe X" the average person isn't going to risk fighting back with their own set of facts, and is possibly going to pay too much. Personally I don't share the anti-tax advocate's world view or opinions, but I understand the argument and especially understand the danger of argument #2. I'd still be in favor of this law though.