The Trump administration on Wednesday proposed a wide-ranging tax overhaul that would slash taxes for businesses and simplify income taxes for individuals and households. The proposal is a barebones outline rather than a detailed plan, leaving many things to be worked out in negotiations with Congress.

What We Know: Here are the five most important things we have learned from the proposal:

A Much Bigger Standard Deduction:

The administration’s wants to double the standard deduction for individuals and households, exempting far more income from taxation. The change would raise the deduction for couples from $12,700 to approximately $24,000 and raise the deduction for single filers from $6,300 to $12,600.

“A married couple will not have to pay taxes on the first $24,000 it earns,” National Economic Council Director Gary Cohn said in a press conference introducing the proposal.

The larger standard deduction reduced the value of itemized deductions, such as the deductions for charitable giving and mortgage interest, because the tax savings from these is proportional to a household’s marginal tax rate. This minimizes the impact on households from the elimination of most itemized deductions included in the plan and decreases the distorting effects of the mortgage interest deduction.

Because doubling the standard deduction would significantly reduce the benefits of itemizing for most taxpayers, it also has the effect of simplifying the tax system. Currently, less than one-third of tax filers, or 45 million households, itemize their deductions. An analysis of a similar proposal by The Tax Policy Center last year estimated that the combination of eliminating most itemized deductions and doubling the standard deduction would result in 38 million households who would otherwise itemize deciding to opt for the standard deduction.

According to the Committee for a Responsible Federal Budget, a group that is critical of the proposal, this will result in households and individuals paying $1.5 trillion less in taxes over the next ten years.

A Lower Top Rate and Fewer Tax Brackets:

The proposal calls for the number of tax brackets to shrink to three from seven, with marginal rates of 10 percent, 25 percent, and 35 percent. Currently, marginal tax rates start at 10 percent and rise to a top rate of 39.6 percent.

Keeps Charitable Giving and Mortgage Interest Deductions, Eliminates the Rest:

Trump’s plan would leave in place the deductions for mortgage interest and charitable contributions while eliminating other deductions, including the deduction for state income taxes that benefits residents of high-tax states.

The impact on most households of eliminating those deductions, however, will be cushioned because of the rise in the standard deduction and the reduction of the top rate, as the value of deductions is a function of the marginal tax rate. The loss of the ability to deduct state income taxes might also incentivize wealthy Americans in high tax states to lobby local lawmakers for lower tax rates.

Keep in mind that only one-third of filers currently itemize. And with the increase in the standard deduction, that number would certainly shrink. Those households most likely to be hurt by the loss of itemized deductions are those with very high incomes, many of whom will see their taxes fall because of the decline in the top rate.

A Big Tax Cut For Businesses Large and Small:

The plan would cut taxes on business income dramatically. The corporate tax rate would fall to 15 percent from 35 percent.

The tax cut for limited liability companies, partnerships, and other so-called “pass-through” businesses would be even steeper. These don’t pay corporate taxes, instead, their income is “passed-through” to their owners, who pay personal income taxes where the top rate is currently 39.6 percent. Trump would allow this income to be taxed at the same 15 percent rate that he has proposed for corporate income.

Business taxes would also become “territorial,” meaning future profits earned outside the U.S. would not be subject to U.S. taxes. Currently, the U.S. has a worldwide tax system under which corporations must pay taxes on all income no matter where their profits are earned, with deductions for taxes paid to foreign governments. But because the tax is only applied when the profits are “repatriated” or brought to the U.S., corporations can defer paying taxes on overseas profits indefinitely by stockpiling the profits abroad. This discourages U.S. businesses from re-investing foreign profits in the U.S.

Kills the Alternative Minimum Tax, the Obamacare Investment Tax, and ‘Death Tax’:

The administration’s plan also calls for the abolition of the Alternative Minimum Tax, a sort of secondary tax code originally designed to prevent very wealthy Americans from using deductions and loopholes to avoid paying taxes. It adds complexity to the tax code and, because it wasn’t indexed for inflation until recently, is no longer only applicable to the super-wealthy. According to the Tax Policy Center, it hits around 30 percent of households with incomes between $200,000 and $500,000.

The plan would eliminate the estate tax, better known to conservatives as the “death tax.” This applies an additional tax to those who die with an estate worth more than $5.49 million. Many of the wealthiest families, however, avoid the tax by using trusts and other tax shelters. As a result, it is expected to apply only to around 11,000 in 2017, according to the Tax Policy Center. Many of these are likely to be less sophisticated wealthy individuals or those whose wealth is tied up in something like a family farm rather than in liquid securities more easily placed in a trust.

It would also eliminate the 3.8 percent tax on some investment income that was introduced as part of the Affordable Care Act.

And What We Don’t Know: There are still many unanswered questions about the tax plan.

Which Income Levels Apply To Which Brackets?:

The administration proposal calls for the income tax brackets to fall from seven to three, but it doesn’t reveal where the thresholds for each bracket will fall. Ideally, the thresholds would be set so that marginal taxes at every level would be reduced. A similar plan introduced by Capitol Hill Republicans last year had a 12 percent rate apply to single filer income between $12,000 and $49,650, a 25 percent rate apply between $49,650 and $202,150, and a 33 percent rate beyond that.

What Happens To Corporate Cash Stockpiled Abroad?:

To avoid paying U.S. taxes on foreign earnings, U.S. corporations have stockpiled large amounts of cash abroad. The Trump administration has signaled that it would like to put in place a program to encourage companies to repatriate that money. Proposals for this in the past have included a “repatriation holiday,” a sort of temporary tax amnesty for the stockpiled earnings. There were no details about the approach the Trump administration would take in Wednesday’s framework.

How Will The Child Care Tax Break Work?:

The Trump administration’s plan mentioned a tax break for child care expenses, but it didn’t go into any detail about this. Structuring a child care tax break can be tricky because conservatives are wary of anything that might penalize stay-at-home moms who don’t have to make cash outlays for things like daycare.

What Will It Cost?:

Without further details, it is very hard to estimate the budgetary cost of the tax proposal. The Committee for a Responsible Federal Budget (CRFB), a deficit hawk pressure group, estimated that it would cost between $3 to $7 trillion.

Speaking on background, administration officials have said the plan could cost as much as $4 trillion in lost revenue but that economic growth would more than makeup for this. Mnuchin said this week that the plan will “pay for itself.” The CRFB has said that GDP growth would have to rise to 4 percent to achieve this, a rate it regards as unrealistic.

While it is unlikely that official budget estimates will declare the tax plan to be “revenue neutral,” that may not matter. Interest rates are very low, which makes budget deficits more affordable. And even after the Trump administration introduced its proposal, the bond market showed no signs that it anticipated rates or inflation to rise much even over the very long term.

In light of this, the Trump administration could push for tax cuts now and offer to work with lawmakers later to find ways to reduce projected deficits.

Will This Pass?:

The failure of the efforts to repeal and replace Obamacare have many skeptical about the Trump administration’s ability to pass sweeping legislation, despite Republican control of the House, Senate, and White House. Others say that the earlier failure has made the need to “score a win” on tax reform even more pressing.

Unless the tax plan attracts Democratic support in the Senate, it would have to be passed using the “reconciliation” procedures that allow legislation to proceed with a party-line vote. But to qualify for this, the plan would have to be judged not to increase budget deficits outside a ten-year window. This could lead to Republicans attempting to sunset some of the changes, making the tax cuts temporary to limit their long-run effect.

The Trump administration may also encounter resistance from deficit hawks in the Republican Party, many of whom have historically insisted that any tax cuts be “paid for” with spending cuts or increased revenue. The Trump administration will have to convince these Republicans that it would be far better to accept a rising deficit than to risk the wrath of Republican voters by rejecting a massive tax cut for businesses and families.