To prevent such exploitation, the Ways and Means Committee would stop contributions to retirement accounts once they reach $10 million.
In other areas, the committee appears to be making only glancing blows at the wealthiest Americans. Former President Barack Obama, Mr. Trump and Mr. Biden have all vowed to close the so-called carried interest loophole, in which private equity managers pay low capital gains taxes on the fees they charge clients, asserting that the money is not income because it is drawn from their clients’ investment gains.
Senate Democrats have proposed closing the loophole completely, saving Treasury $63 billion over 10 years. The House proposal would merely limit the practice, forcing Wall Street financiers to hold their clients’ investment gains for five years before claiming them as capital gains and cashing out. It would save $14 billion, a fraction of the Senate proposal.
Another item missing from the House plan: a measure to tax inheritances more aggressively. Mr. Biden and many other Democrats want assets such as stocks and real estate to be taxed when they are inherited by wealthy heirs, based on the gain in value from the time the original owner purchased them. Under current law, such assets face capital gains taxation only when they are sold, according to their worth when they were inherited, allowing all the gain in value over the lifetimes of the superwealthy to go untaxed as long as they are passed on to heirs.
But the new proposal faced a fierce lobbying campaign, led by rural Democrats like former Senators Heidi Heitkamp of North Dakota and Max Baucus of Montana. Representative Richard E. Neal of Massachusetts, the Democratic chairman of the Ways and Means Committee, left it out.
To some liberals, Mr. Neal’s pragmatism felt more like surrender.
“America’s billionaires are popping Champagne tonight as the House Ways and Means Committee — led by Chair Richie Neal — fails the president, fails the country and fails history,” said Erica Payne, the president of Patriotic Millionaires, a group of wealthy liberals that embraces much higher taxes on the rich.
Some Democrats expressed surprise on Monday at Mr. Neal’s political calculations.
“A wealth tax? I don’t know anyone who says that’s not working for them politically,” said Representative Donald S. Beyer Jr., Democrat of Virginia and a member of the committee.