The independent Institute on Taxation and Economic Policy said on Monday that the top 1 percent of income earners, those who make just under $500,000 a year or more, would receive nearly half of the bill’s tax benefits a decade from now. That group of taxpayers would consistently see income gains from the bill, and those gains would grow from 2.4 percent in 2018 to 2.5 percent in 2027, the institute said. Every other income group would see its percentage gains dwindle over time as a result of changes the bill makes to inflation calculations for certain tax benefits, and the fact that a middle-class tax credit it creates would expire after five years.

Still, the bill does not treat all top 1 percenters equally. An analysis using the economic modeling software TaxBrain suggests that a quarter of tax filers earning $1 million or more would see their taxes go up next year if the bill becomes law. No other income group would initially see that high a share of tax filers with tax increases.

The House bill mixes steep reductions in business tax rates with a blend of rate cuts and loophole closures on the personal side, producing a mixed bag for taxpayers up and down the income spectrum, but delivering the largest gains, in dollar and percentage terms, at the top.

“While every income group sees a benefit on average under this plan, high-income filers get the most relief, particularly those making above $1 million,” said Ernie Tedeschi, an economist at Evercore ISI, who has modeled the effects of the proposal. “That’s true even before taking into account the impact of the corporate tax cuts.”

Mr. Tedeschi said those results were intuitive, given the nature of the bill, which includes the repeal of the Alternative Minimum Tax and the reduction in rates for pass-through income to 25 percent from the top 39.6-percent rate now. That will amount to a large cut for many wealthy business owners.

High-income taxpayers who earn “labor income” — money paid for work — would not fare as well. The bill eliminates many deductions popular with higher-income taxpayers, including those for state and local income taxes paid. It would also cap at $500,000 the amount of new mortgage debt on which interest could be deducted, down from $1 million. And those high-earners are stuck with the top personal income tax rate of 39.6 percent — though the threshold for paying it rises to $500,000, from $418,000 today, for individuals and $1 million, up from $471,000 today, for couples.

The bill also effectively increases that top rate even further by preventing those taxpayers from taking advantage of lower marginal rates along the income scale, a benefit which all other taxpayers enjoy. The bill proposes three individual income tax brackets: 12 percent for married couples earning up to $90,000; 25 percent for those earning up to $260,000 and 35 percent for those earning up to $1 million. A couple earning $350,000 would pay 12 percent on the first $90,000 of that income, 25 percent on the next $170,000 and 35 percent on the remaining $90,000. Those earning more than $1 million would gradually lose the benefits of the 12 percent bracket as their incomes rose.