It should also be noted that if the vast majority of people do nothing special on their taxes and just accept the government's assessment, then that leaves a much smaller group of people to be audited. And a much larger portion of those people will be those who are trying to weasel their way out of paying their share. Right now, with the IRS being criminally underfunded, they only focus on low hanging fruit, the small fries. With those people being boiler plater auto-accepting tax payers, that would mean the IRS has no reason to audit them and can focus on the big boys where the real cheats are. That's another big reason we do not have that sort of system and why the IRS is currently so underfunded (despite every dollar spent on the IRS generating between 5 and 9 dollars in revenue from tax fraud/evasion). Those kinds of people pay to make sure it doesn't happen.