The Tax Cuts and Jobs Act documents wait on the dais of the House Rules committee at the U.S. Capitol on Dec. 18, 2017. (William P. O'Leary/Washington D.C.)

The final Republican tax bill contains slightly more in tax relief for the middle class than did its earlier versions, but the wealthy remain the biggest winners in the plan, a nonpartisan tax analysis group concluded Monday.

The bill will move to the House floor Tuesday after passing through the House Rules Committee on Monday evening. Republicans plan to send it through the House and Senate this week and forward it to President Trump, who for months pushed his party to give him a tax-cut bill by Christmas.

The GOP bill would lower taxes for 95 percent of Americans in 2018, but on average the cuts for the highest earners far exceed those of people making less, according to the Tax Policy Center.

In 2018, taxpayers earning less than $25,000 would receive an average tax cut of $60, the center found. Those earning between $49,000 and $86,000 would get an average cut of about $900; those earning between $308,000 and $733,000 would receive an average cut of $13,500; and those earning more than $733,000 would receive an average cut of $51,000.

"In general, higher-income households receive larger average tax cuts as a percentage of after-tax income," the report said.

The bill before Congress now is a compromise between a measure the House passed in November and one the Senate passed earlier this month, though it also included some provisions that did not come from either previous version.

Among the three bills, the House bill was most skewed toward the wealthy, while the final version was the least, said Tax Policy Center director Mark Mazur, who stressed that the bill's many provisions complicate sweeping assessments of its impact.

In the final version of the bill, lawmakers reduced the tax rate on income above $1 million, but they also added new benefits for low- and middle-income families seeking to take advantage of a newly expanded child tax credit.

"The Senate bill was a little less regressive than the House bill, and this appears to be a little less regressive than the Senate bill," Mazur said. "But, overall, the conference agreement is more regressive than current law."

As written, the bill becomes less generous for individuals in later years, as many of the tax benefits for individuals have set expiration dates. By 2027, 53 percent of Americans would pay more in taxes, according to the TPC. Republicans have argued that future lawmakers will intervene to stop the cuts from expiring, noting that many of the tax cuts signed into law by President George W. Bush were initially set to expire but later extended by Congress and President Barack Obama.

The bill would also make large cuts to the estate tax, a levy on inheritances charged only to the very wealthy. Under the plan, a couple could pass on as much as $22 million in assets without paying the tax.

The backbone of the GOP plan is a reduction in the tax rate paid by corporations to 21 percent, far below the existing 35 percent rate. That rate cut is not set to expire.

The plan has been controversial since its inception and is unanimously opposed by congressional Democrats, who have derided it as a giveaway to the wealthy and corporations. Republicans argue the measure will spur economic growth, increasing employment and wages and bolstering the fortunes of the middle class, although the administration's growth projections have far outstripped those of nonpartisan analysts.

Multiple polls have suggested broad public skepticism of the plan, with clear majorities of respondents saying they think corporations would be its biggest beneficiaries.

The plan is projected to add more than $1 trillion to the deficit over 10 years.