Despite all the attention paid to President Obama's recent budget proposal, at least one important section of the proposal has gone largely unnoticed. Buried within an appendix, and blandly titled "Performance Measures and the Economic Effects of Tax Expenditures," this section is supposed to explain the administration's efforts at figuring out whether the $1 trillion doled out through special tax breaks each year are worth their cost. Unfortunately, for the second year in a row, the Obama administration has chosen to simply copy-and-paste the Bush administration's language on this issue, complete with all the same promises about what will be done at some point over the "next few years."

Do capital gains tax breaks encourage economic growth? Does the research tax credit result in additional research? Are charitable deductions an effective way to encourage giving? Questions such as these have not been studied in a systematic way by our government, despite numerous promises having been made in this section of the president's budget for over a decade.

Each year the government effectively "spends" more on special tax breaks, or "tax expenditures," than it does on the entire discretionary spending budget (i.e. the part of the budget not devoted to Social Security, Medicare, Medicaid, etc). These tax breaks are usually enacted with the same goals as spending programs, such as promoting education, housing or renewable energy. But despite their similarities, tax expenditures receive only a small fraction of the scrutiny directed at regular spending.

With deficit-reduction quickly climbing the list of legislative priorities in Washington, the need to take a closer look at tax expenditures is growing. The House of Representatives already has shown interest, having passed legislation that extends 50 expiring tax expenditures only on the condition that a nonpartisan study of each provision will be conducted. The administration, however, is in better position to conduct such studies on a comprehensive basis, and the increasingly bleak budgetary outlook demands that it do so.

During more favorable budgetary times, both political parties were more than willing to enact new tax expenditures (and to continue existing tax expenditures) at every opportunity. The desire to "cut taxes" while simultaneously "taking action" on education, housing, or some other issue has proven to be irresistible on many occasions.

But with the budgetary outlook continuing to sour, policymakers will soon have to acknowledge that fiscal sustainability can only be restored after a close re-examination of the nation's priorities. Both liberals and conservatives alike have good reason to include tax expenditures within the scope of this re-examination.

For conservatives, tax expenditures are an attractive candidate for additional scrutiny because such programs often are little more than government spending that just so happens to be written into the tax code. While some politicians like to frame the elimination of a tax expenditure as a "tax hike," for a true conservative, eliminating a tax expenditure is far preferable to an increase in tax rates.

Liberals also should respond favorably to efforts to scrutinize these programs. While tax expenditures benefit a wide variety of people, they often are skewed toward upper-income individuals and corporations — unlike most regular government spending programs. If liberals are forced to accept cuts to government programs, reducing tax expenditures often will be more palatable than cutting ordinary spending or entitlement programs.

To its credit, the Obama administration already has begun to turn its attention toward some tax expenditures.

In fact, more than three dozen tax expenditures, mostly benefiting corporations, were singled out for elimination or reduction in its Feb. 1 budget proposal. This, however, is only the tip of the iceberg.

Pushing forward with tax expenditure review could allow for the identification of numerous additional tax expenditures that should be brought to the chopping block. But those reviews must be started soon if they are to have any role in the upcoming debates over the budget deficit.

Carl Davis is a senior analyst with Citizens for Tax Justice in Washington, D.C.