Supercommittee members Sen. Pat Toomey and Rep. Jeb Hensarling are taking flak from some conservatives for proposing a deal including increases in "revenues," and a Washington Post reporter had some fun insinuating that they were backing a tax-rate increase.
As this is written, no one knows what the supercommittee will do (or not do), but it's worth taking a look at what Toomey and Hensarling actually were talking about. It may not matter now, but could after 2012.
They were raising the possibility, as Barack Obama's Bowles-Simpson commission did last December, of a tax reform bill that, like the 1986 tax reform act, would eliminate tax preferences and lower tax rates.
The 1986 bill was passed with bipartisan support, and there's a potential for bipartisan support again.
The problem in putting such a measure together is that most really egregious tax preferences don't add up to much money. Just as the big money for long-term spending cuts must come from changes in entitlements -- Social Security, Medicare, Medicaid -- so the big money you can get from eliminating tax preferences comes from three provisions that are widely popular.
The three are the charitable deduction, the home mortgage interest deduction, and the state and local tax deduction.
The charitable deduction should probably be off the table. The Obama administration has proposed reducing it for high earners. But this obvious attempt to channel flows of money away from the voluntary sector and toward the federal government went nowhere even when Democrats controlled the House and had a supermajority in the Senate. It's anathema to many Democrats and just about all Republicans.
The home mortgage interest deduction may seem similarly sacrosanct. But the fact that the vast bulk of the "tax expenditures" -- the money the government doesn't receive because taxpayers deduct mortgage interest payments from total income -- goes to high earners with big, expensive houses.
Traditionally it's been argued that government should provide incentives for homeownership because homeowners more than renters have a stake in their community. But it's obvious now that we have over-incentivized homeownership, with government encouraging loans to noncreditworthy borrowers.
At the same time, high earners don't need an incentive to buy a home. If we limit the mortgage interest deduction to some amount near the median housing price, some folks will still buy $1 million homes, though they may finance them a little differently. And the government can get more revenue without an economy-crushing tax rate increase.