Almost everyone thinks we should broaden the tax base; that is, reduce the number and size of tax deductions, exclusions and credits.
The Bowles-Simpson fiscal-reform plan went after tax breaks so aggressively it was able to slash the deficit and still cut tax rates. Most conservative reformers follow that model.
Even economists who aren't conservatives generally say the government should raise revenue by getting rid of tax breaks before it raises rates. That is the position Republican leaders in the House and Senate have taken, too.
As pleasing as it is to find a consensus in this polarized era, this one is mistaken. It would be either undesirable or politically impossible to reduce the largest loopholes in the code.
At the top of the Congressional Budget Office's list of the biggest tax breaks is the exclusion of employer-provided health insurance from the income and payroll taxes. You pay taxes on your wages, but not on your benefits, encouraging employers to provide more of your compensation in the latter form.
The policy is something of a historical accident: It arose after employers used benefits to evade World War II-era wage controls. If we were designing a code from scratch, we would certainly tax these benefits.
We have had this break for an awfully long time, though. It would be disruptive, as well as unpopular, to get rid of it. The exclusion should be modified so that it doesn't reward people for choosing more expensive policies, and so that people who have no access to employer plans can buy insurance for themselves. What we won't do is get big savings from shrinking this tax break, and we shouldn't try.
Several other large breaks benefit savings and investment, the most famous being the low tax rate on capital gains and dividend income, compared with labor income. In a way, though, these aren't tax breaks at all: They are a partial corrective to the code's bias against saving and investment. A better code would just tax consumption, which would mean a smaller tax base.