One proposal popular with economists is treating some portion of employer-provided health insurance as taxable income on a filer’s tax return, an idea proposed by Hillary Clinton and accepted by many Democrats during the 2008 campaign. If a health plan is valued at more than $14,000, for example, the sum above that could be treated as taxable income.

Another idea would be to limit how much mortgage interest, state taxes or charitable giving can be deducted from taxes by high-income earners. The New Year’s deal started phasing out some of the tax exemptions claimed by high-income earners and limiting their tax deductions. This could gain in popularity because tax rates remain unchanged and middle-income Americans would not be affected.

A bipartisan presidential commission in 2010 favored scaling back mortgage-interest deductions, in part because they effectively subsidize the wealthy by offering them a bigger discount off a higher tax rate. The problem is that rolling this program back is fraught with risk in today’s impaired housing market.

“How do you phase it in? The more you cut back, the more effect it has on the housing market,” noted Roberton Williams, a senior fellow at the Tax Policy Center, jointly run by the center-left Brookings Institution and the centrist Urban Institute. “How do you deal with that transition period?”