In 2008, the AGI of the top 10 percent of earners was $3.9 trillion, represented in just 14 million tax returns, as reported here.
Assuming these are individuals (which cannot be true because only 140 million returns in total were filed that year but let's make the assumption anyway), about $2.4 trillion of that money would have escaped Social Security taxation above the threshold limit, rounded, of $107K of income per year.
About $1.5 trillion of the $3.9 trillion would have been taxed for Social Security purposes. Again, I'm using adjusted gross income which is also not going to be an accurate measure, but it'll have to do for this back of the envelope calculation.
6.25 percent of the remaining $2.4 trillion comes to $150 billion in lost revenue for Social Security in 2008, way ahead of the top tax loss expenditures, medical insurance at $131 billion, pensions at $117 billion, and your mortgage interest at $88 billion. See the data here.
The Super Committee, aka The Gang of Twelve, is interested in all proposals to raise revenues by closing "loopholes," like your mortgage interest deduction. Yet that's only fourth on the list of "lost" government revenues. The biggest loophole goes to the richest 10 percent of earners.
We're taxed enough already. Cut the spending instead.
