Two weeks ago, Senators Baucus and Hatch, respectively the chairman and ranking minority member of the Senate Finance Committee, sent a “Dear Colleague” letter to solicit input on which tax expenditures to keep in the tax code. They are proposing a “blank-slate” approach for tax reform—eliminate all tax expenditures from the tax code and then add in the ones that can be justified. It’s a positive development that the senators aren’t constraining the initiative to be revenue neutral, but what sounds like a novel and fresh approach to tax reform that broadens the tax base and simplifies the tax code, both laudable goals, will likely obtain neither.

My guess is the “blank-slate” approach to tax reform is doomed to failure. 100 senators, backed by thousands of lobbyists, are all but guaranteed to come up with a plan as complicated as the current tax code. Perhaps serious tax reform is not in the cards for the 113^th Congress.

Tax expenditures are tax credits, tax deductions, and exclusions embedded in the tax code, which reduce a taxpayer’s tax liability; they are often referred to as loopholes. According to the Joint Committee on Taxation, there are over 200 tax expenditures affecting individuals, and they are estimated to reduce Fiscal Year 2014 tax revenues by $1.1 trillion. “Broadening the base” refers to the elimination or reduction of these expenditures, and is held up as the gold standard for tax reform. Depending on who you ask, increased revenue from broadening the base should be used to reduce tax rates, reduce deficits, or increase expenditures on education, infrastructure and the social safety net.

Base broadening sounds easy, but may prove difficult once we examine the list of tax expenditures. Senators Baucus and Hatch have stated “that all special provisions are out unless there is clear evidence that they: (1) help grow the economy, (2) make the tax code fairer, or (3) effectively promote other important policy objectives.” Not said, but certainly at the forefront of almost every politician’s mind is a fourth criterion: (4) effectively promote important political objectives such as reelection.

The 18 largest tax expenditures are listed in the table along with their estimated FY2014 revenue loss (in some instances I have combined tax expenditures into a single item, such as charitable contributions). A quick glance at the list suggests that all would be added back into the code based on the fourth criteria (political survival). It is easy to see why one senator or another will offer real or fanciful arguments to justify retaining a tax expenditure using one of the criteria. So we have just added back 18 of over 200 tax expenditures to the tax code. No big deal, until you realize that these 18 tax expenditures add up to $966.6 billion, or 87 percent of the revenue loss of all 200+ tax expenditures. As a matter of fact, just the 10 largest tax expenditures account for about 70 percent of the aggregate revenue loss of all tax expenditures. Keeping just these 18 means we have simplified the tax code—a worthy goal in and of itself—but we haven’t broadened the tax base by much. Tax revenue would increase by about $140 billion in FY2014, or more than $1.4 trillion over 10 years, which is not enough to significantly reduce tax rates (but could eliminate much of the unnecessary and ill-advised budget reductions enacted in the 2011 Budget Control Act).

How likely is it that the remaining 200+ tax expenditures will be added back in? Past experience suggests that it is highly likely. Every year several tax provisions expire; these tend to be called “extenders,” because most are extended for another few years by what has become known as the annual extenders bill. The last extenders bill was the American Taxpayer Relief Act of 2012 (ATRA), passed by the 112^th Congress and signed by President Obama last January. The primary purpose of ATRA was to extend the 2001 and 2003 Bush-era tax cuts for the vast majority of taxpayers, but it also included the extension of 52 expired or expiring tax provisions. This goes on every year. Getting rid of even temporary tax provisions has proven to be an impossible task for Congress (it should be noted that the extenders bills come out of the two tax writing committees, the very ones that will produce any tax reform legislation).

So, I don’t think the 113^th Congress will enact serious tax reform. But they might at least be able to pare down the list of tax expenditures and increase tax revenue. Otherwise, if base-broadening is a nonstarter, then higher tax rates will be required to raise the revenues needed to fund important federal programs, services, and investments.