To best understand this spending aspect of the current budget negotiations in Washington, we must answer one crucial question: how much taxation on the top income-earners would be required to fully fund the present level of government spending?

To do so, we must first make the unreasonable assumption that the rich will not respond to confiscatory tax rates and hide money from being taxed.  This is unreasonable because no scheme of taxation since WW2 has been able to capture more than 21% of GDP.  With current spending levels around 23% of GDP, history suggests that no level of taxation we have yet tried would actually fully fund our current level of spending.  But if we indulged some "static scoring" and assumed a static tax base, what would a zero-deficit, soak-the-rich taxation scheme look like at current spending levels?

For example, what would a 100% income tax on all those who earn over $10 million amount to?  I'm not taking about a wimpy marginal rate, where one might tax only those dollars of income over $10 million (leaving the taxpayer $10 million).  No, I'm saying you find all those who made more than $10 million and take every last penny -- an absolute tax of 100%.

Using 2009 data, the IRS says that 8,274 tax returns were filed with incomes over $10 million.  The total amount of income on those returns was $240.1 billion.

Our federal government alone is spending more than $10 billion a day.  Thus, a 100% confiscation of all income of those making more than $10 million would amount to less than 24 days of federal spending.

If we drop that "tax" point down to $1 million, the picture changes radically.  The IRS says 236,883 Americans filed returns with more than $1 million in income.  They reported a total income of $726.91B.  While that is a lot of money, it's less than just Medicare and Medicaid, which cost $1 trillion together.

Confiscating 100% of all income from those who made over $1M funds the federal government for 72 days.

Therefore, we have to go farther down the income ladder.  Merely taking 100% of what the "millionaires and billionaires" are reporting as income won't do it -- despite the campaign rhetoric from the president.

Let's move the bogey down to $200,000 in income.  That's even lower than the $250,000-earners President Obama thinks should pay more.  What happens if we confiscate 100% of all the income for people who make more than $200K?

The IRS received 3,924,490 tax returns showing an income over $200K.  These returns represent a total income of $1.964 trillion!  That's a huge amount of money.

But it's still not enough.  The federal government is spending about double that this year.

Confiscating 100% of the income from those who made more than $200K funds the federal government for only about six months.

Even if you think that $200K per year is filthy rich, taking all of the income of such people for an entire year isn't even close to funding our federal government for a full year -- never mind state and local government.

The next step down in the 2009 IRS data is the $100K income point.

There are a lot more taxpayers reporting over $100K income than there are over $200K.  The IRS says that only 2.8% of returns reported over $200K in income, but 12.4% of returns reported over $100K in income.  So even though the cutoff is half as much income, it represents about five times as many taxpayers.

The data indicate that 17,446,537 tax returns showed an income over $100,000.  These returns represented a total income of $3.765 trillion.

Estimated 2012 spending comes in at $3.796 trillion (refer to page 205 here).  This is still $30 billion more than a 100% confiscation of the annual income of all Americans that reported more than $100K of income for 2009.

The bottom line is that we cannot fund our current levels of spending even if we make unrealistically charitable assumptions about taxpayer response to confiscatory tax rates and confiscate the entire annual income of every American who made more than $100K in 2009.

Justin Hohn is a former Air Force officer who blogs at www.justinhohn.typepad.com.