Millions of Americans wrote checks to Uncle Sam on Monday for their 2012 federal tax bills. When all the counting is done, the federal government will collect more than $2.7 trillion in tax revenues, the most ever collected by the IRS in one year. Before they signed their checks, though, those same Americans devoted more than 6.1 billion hours preparing their tax records and returns, and they spent more than $168 billion on tax compliance, according to the Taxpayer Advocate Service, a division of the IRS.

It is impossible to calculate with precision the opportunity cost -- what could not be done with the time and money -- of those billions of hours and hundreds of billions of dollars spent on tax preparation and compliance. But here's one way of looking at it: That $168 billion could have provided $60,000 college scholarships to 2.8 million young Americans, and the 6.1 billion hours would have covered the 120 credit hours typically required for each of them to earn an undergraduate degree.

As illustrated by the Charticle nearby, for every tax dollar spent on protecting the U.S. from its enemies, the federal government spent $3 on social welfare programs of all descriptions, including Social Security, Medicare, Medicaid, veterans benefits, food stamps, civil service retirement benefits and health care. Whether one believes that is the proper ratio between defense and social welfare spending, these data should end the hoary myth that America spends more on guns than it does on butter.

One good thing about April 15 is that it often provides the occasion for useful debates among officials and the citizenry on tax policy. Monday was no different, as seen, for example, in University of Chicago Professor John H. Cochrane's Alternative Maximum Tax proposal in the Wall Street Journal. This would put a ceiling on the combined total of taxes paid by each American to all levels of government in any one year. The preface to the Cochrane AMT would be a national conversation on these questions: "How much is the most anyone should have to pay? When do taxes indisputably start to harm the economy and produce less revenue -- when government takes 50% of people's income? 60%? 70%?"

Similarly, during the Fair Tax/Flat Tax Reform Forum at the University Club in Washington, Rep. Michael Burgess, R-Texas, and Rep. Rob Woodall, R-Ga., offered an impressively civil and informative discussion of the respective merits of their favored approaches. Burgess said Americans should be able to choose between the current tax code, with its bewildering array of deductions and special-interest tax breaks, and a new flat tax that would eliminate all of them. Woodall, a Fair Tax supporter, said it is vital that every American have "skin in the game" of funding government, as would occur with a Fair Tax. Between them, the professor and the congressmen describe three sound principles of a genuinely fair tax system -- everybody has a stake in it, everybody gets to choose the old or the new system, and everybody knows when government gets too much.