Wiping out all tax expenditures — the official name for the deductions, credits and other loopholes addling the tax code — for the top 2 percent of earners would raise about $2 trillion over 10 years. (Tax expenditures for all households cost the government about $1 trillion a year, because middle-class and low-income families also benefit.)

But doing so would mean that a family earning just over $250,000 a year might face a sharply higher tax bill than a household earning just under that amount. A phase-in, which most analysts consider unavoidable, might slash $300 billion from the revenue pot, leaving roughly $1.7 trillion, just over what the White House seeks.

That means that any proposal raising $1.6 trillion would involve getting rid of nearly every loophole or break in the code for high-income families — not just itemized deductions, but also preferential rates on investment income and every tax credit the wealthy can currently claim.

There would be no deduction for charitable giving, or close to none, angering wealthy donors and nonprofit directors. The home mortgage interest deduction would vanish, hurting the housing market just as it has started to turn around. Preferential tax treatment of capital gains and dividends would disappear, probably throwing the markets into a sell-off. The top 1 percent of earners might see their after-tax income fall as much as 19.8 percent, according to calculations by the Tax Policy Center.

This is a large part of the reason that the White House has argued for allowing the top two marginal rates to rise to the Clinton-era levels, with a top rate of 39.6 percent. Such an increase would reduce the deficit by nearly $1 trillion over 10 years and allow for a deal that caps deductions, rather than eliminates all of them.