In recent weeks, Donald Trump has torn up the usual Republican script on taxes. He has called for tax cuts for the middle class while complaining of “outrageous” tax breaks for multimillionaires, especially hedge fund managers.

On Wednesday, Jeb Bush joined Mr. Trump by issuing a tax plan that ends certain tax breaks for hedge fund managers. But aside from that detail, Mr. Bush’s plan stays very much on script for Republican tax plans: It cuts taxes for almost everyone who pays income tax, with by far the largest tax cuts at the top.

According to an analysis by The New York Times, Mr. Bush’s tax plan would reduce the effective tax income rate on filers making $10 million or more per year to approximately 21 percent, down from 26 percent in 2013, the most recent year for which data are available. The average taxpayer in this group earned $29.2 million in 2013, meaning the plan proposed by Mr. Bush would have saved them an average of $1.5 million that year.

High earners were hit with a large tax increase in 2013, because of the partial expiration of the George W. Bush tax cuts and new taxes in the Affordable Care Act. Jeb Bush’s tax plan would lower the tax burden on the wealthiest to near the levels that prevailed under his brother.

The reason Mr. Bush’s plan cuts taxes for the rich so much is simple: He would cut the top tax rate on regular income by almost 12 percentage points and on capital income by almost 4 points. The current seven-bracket tax system, with rates from 10 percent to 39.6 percent, would be replaced with just three brackets of 10, 25 and 28 percent. Maximum tax rates on investment income would drop from 23.8 percent to 20 percent.

Mr. Bush would eliminate and cap many deductions and tax a greater share of top earners’ income. However, The Times’s analysis finds that these base expansion effects would be small relative to the tax rate cuts.

Mr. Bush’s plan wouldn’t cut taxes just for the rich. In part by doubling the standard deduction, it would cut income taxes on all income groups and most tax filers. By expanding the Earned Income Tax Credit, it would cut taxes for some who currently pay no federal income tax. It would also significantly cut the corporate income tax.

This tax-cuts-for-nearly-everyone approach is a major departure from Mitt Romney’s 2012 tax plan, which promised deep tax rate cuts without increasing the deficit; it led to claims by opponents that he’d need to raise taxes on many middle-income taxpayers in order to put the same amount of money in federal coffers.

Mr. Bush is making no such promise of revenue neutrality. According to an estimate prepared by prominent conservative economists, including Glenn Hubbard and Martin Feldstein, his plan would reduce government revenues by $3.4 trillion over 10 years before accounting for economic feedback effects, making it somewhat larger, relative to the economy, than his brother’s tax cut packages. However, those economists contend the tax plan would add 0.5 percent a year to economic growth over a decade, partly offsetting the revenue loss.

Here’s the math behind The Times’s estimate of the Bush plan’s effects on the highest earners. Taxpayers earning $10 million or more (the highest income category reported by the I.R.S. in its income tax statistics) paid federal income taxes equal to 26.1 percent of their income in 2013. That was the first year in which high-earning taxpayers faced tax increases related to the Affordable Care Act and the partial expiration of the Bush tax cuts.

Under Mr. Bush’s plan, these taxpayers would face a nominal tax rate of 28 percent on ordinary income. However, even after the rule change on carried interest, about 60 percent of these taxpayers’ income would enjoy a preferential rate of 20 percent because it consists of capital gains, interest payments, dividends and other similar returns on capital. Taking a weighted average of those rates results in a blended rate of 23.1 percent. Itemized deductions (mostly for contributions to charity, which Mr. Bush’s plan would not impose new caps on) would reduce that rate to about 21.1 percent, five points below the actual figures for 2013.

According to examples provided by the Bush campaign, typical taxpayers would get tax cuts that raise their after-tax income by amounts ranging from 1.9 percent (for a single adult earning $50,000) to 4.3 percent (for a married couple making $250,000). By The Times’s calculation, taxpayers earning over $10 million would experience a 6.8 percent rise in their after-tax incomes on average under the Bush plan.

Mr. Bush also plans cuts in corporate taxes, which are ultimately borne by individuals. Economists debate exactly how the corporate tax burden is spread between shareholders (in the form of lower after-tax profits) and workers (in the form of lower wages paid by corporations), but consensus estimates generally put the bulk of the burden on shareholders.

The congressional Joint Committee on Taxation estimates that 75 percent of corporate taxes are paid by owners of capital. Assuming that is right, Mr. Bush’s corporate tax cut would constitute an additional significant tax cut for the highest earners. However, many economists also believe corporate tax cuts are more effective than personal income tax cuts at spurring economic growth; a corporate tax cut could drive economic gains that raise pretax incomes for people across the income spectrum, while having direct tax effects that mostly benefit the wealthy.

Mr. Bush has framed the tax plan as part of his effort to achieve 4 percent real economic growth, a figure economists were skeptical could be achieved on a sustained basis when I interviewed them earlier this year. The specific economic effects of this tax plan would depend heavily on how it would be financed.

“If this plan was financed by contemporaneous entitlement cuts, I think it’s clear there would be a significant increase in economic growth,” said Alan Viard, an economist at the conservative American Enterprise Institute. But he said middle-income people might not be better off, despite getting tax cuts.

“Some income groups will be hit by the entitlement reductions that are being adopted under the scenario, and so then obviously you have to take that into account,” Mr. Viard said. “One might ask whether the growth effects are sufficiently big so that those groups come out ahead in the long run, and certainly I think that’s possible, but we don’t know.”

Of course, deep tax cuts wouldn’t have to be financed with spending cuts, at least not right away. They could be financed with borrowing, as was done in the last decade. Mr. Viard argued this approach would provide much less of an economic lift, because the effects of added government borrowing would offset the positive economic effects of tax cuts.